Description:TECHNICAL FIELD
The present disclosure relates to the field of electricity generation. It relates to a method for producing electrical energy, a cell for producing electrical energy, and a system comprising a plurality of said cells. Particularly, the present disclosure relates to all the aspects to produce electrical energy from carbonaceous material using ambient energy.

BACKGROUND OF THE DISCLOSURE
Conventional approaches to generate electricity include combustion of coal, use of solar cells based on silicon technology, graphene-based solar energy traps and the like. However, each of these approaches have certain drawbacks. For example, combustion of coal is a long and circuitous process, with a large leakage of energy at every step. The use of silicon technology for solar panel faces various limitations such as high cost, limited availability of sunlight (especially in the night and in rainy days) and coverage of the panels by dust reducing solar light absorption. Hybrid inorganic semiconductors are in use to increase the efficiency but toxicity of these are well known and to avoid that effect, encapsulated systems have been tried. Graphene-based visible solar energy trap has been tested; however, the solar energy trap technique requires costly silicon technology and mimic only a part of the entire process involved in the fixation of light by leaves.

Two fundamental energy related processes exist on this planet, one is photosynthesis and the other one is respiration. Plant photosynthesis involves two connected complimentary events where, in the first phase, visible sun light initiates the release of electrons that reduce CO2 to sugar and in its complimentary phase, splitting of water by a manganese cluster supplies electrons to the holes to balance the electrons consumed in the reduction process. The release of oxygen in such water splitting process is a bonus for the nature and led to the evolution of respiration-based animal kingdom.

To mimic the first part of the photosynthesis, use of photovoltaic/solar cell to trap electrons from visible solar light has been explored where silicon plays a major role to construct the basic structure of such cell (M. Gratzel, Nature 2001, 414, 338-344). However, the efficiency of photovoltaic cell (silicon technology) faces various theoretical and practical limitations. There is a continuing interest to improve this efficiency by doping and by using newer composites (J. G. Carter, Solar Energy and Solar Panels: Systems, Performance and Recent Developments, Nova Publishers, 2017). However, as discussed above, constraints like non-availability of sunlight during night and rainy days coupled with the initial high cost of these materials limit their global use especially in developing and underdeveloped world.

To avoid leakage of energy associated with combustion of coal, it was argued that if aerial oxygen can combine with carbon, not directly as in combustion, but through some intervening electron carriers, then the stored up energy of the carbon may be converted into electrical energy in the temperature range of 400-500? (W. W. Jacques, 1896, U.S. Patent No. 555,511; hereinafter “the Jacques patent”).

Nikola Tesla in 1901 (N. Tesla, 1901, U.S. Patent No. 685,957; hereinafter “the Tesla patent”) suggested exploiting radiant energy of the earth. An apparatus comprising a condenser and other means was accordingly developed for utilizing radiant energy.

However, there is a need to develop a simple, cost-effective and energy efficient method/system to overcome the problems associated with currently used methods/systems. The present disclosure attempts to address said need.

STATEMENT OF THE DISCLOSURE
The present disclosure relates to a method for producing electrical energy comprising reacting reduced graphene oxide (rGO) with oxygen in presence of ambient energy, wherein the rGO is impregnated with alkali.

The present disclosure also relates to a cell comprising: a) an anode comprising reduced graphene oxide (rGO), wherein the rGO is impregnated with an alkali solution; b) means for introducing oxygen into the cell; and c) a cathode.

The present disclosure further provides a system comprising a plurality of the cells as described above, wherein the plurality of cells is connected in series or in parallel or a combination thereof.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1 shows the detection of potential of about 460 mV in presence of air whereas negligible potential was detected in presence of argon.

Figure 2A shows a hysteresis plot of Temperature vs Potential (voltage) and Figure 2B shows a hysteresis plot of Temperature vs Current in two consecutive cyclic scans from 5? to 65? showing the temperature effect on the output of the associated chemical reactions.

Figures 3A and 3B show exemplary embodiments of a system comprising a plurality of cells with series and parallel connections to glow a LED lamp and to drive a DC motor.

Figure 4A shows a graph of current vs layers of coal containing rGO and Figure 4B shows a graph of current vs surface area of coal containing rGO.

Figure 5 shows cells covered with different coloured filters. The top row shows cells covered with red, yellow, and blue colored transparent sheets from left to right; middle row shows cells covered with green colored transparent sheet and white transparent sheets from left to right; and the last row shows cells covered with a black sheet.

Figure 6A shows the spectrophotometric analysis of formic acid; Figure 6B shows a standard calibration curve of sodium formate; and Figure 6C shows a yellow brown coloration developed on the Whatman filter paper (using iodide oxidation) indicating the generation of peroxide during the redox reaction.
Figures 7(a)-7(d) show analysis of purified low-grade coal: a) FT-IR spectrum, b) Raman spectrum, c) XRD pattern and d) TEM image.

Figures 8(a)-8(d) show analysis of isolated GO from low-grade coal: a) FT-IR spectrum, b) Raman spectrum, c) XRD pattern and d) TEM image.

Figures 9(a)-9(d) show analysis of rGO from low-grade coal: a) FT-IR spectrum, b) Raman spectrum, c) XRD pattern and d) TEM image.

Figures 10(a)-10(d) show analysis of recovered GO after few hours of cell reaction: a) FT-IR spectrum, b) Raman spectrum, c) XRD pattern and d) TEM image.

Figure 11A depicts the picture of a cell; Figure 11B depicts an exemplary embodiment of a system comprising a plurality of cells wherein the individual cells are connected in series to produce higher voltage; and Figure 11C depicts an exemplary embodiment of a system comprising a plurality of cells wherein the individual cells are connected in parallel to produce higher current.

Figure 12 depicts an exemplary embodiment of a system comprising a plurality of cells wherein the individual cells are connected in parallel and series to produce higher voltage and current (individual cell voltage - 450mV; individual cell current - 10mA).

Figure 13 depicts an exemplary embodiment of a system comprising a plurality of cells wherein the individual cells are arranged in stacks to generate 12 volt and 3A, (36W).

DETAILED DESCRIPTION OF THE DISCLOSURE
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising” or “containing” or “has” or “having”, or “including but not limited to” wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification may not necessarily all refer to the same embodiment. It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

As used herein, the term “ambient energy” refers to different forms of natural energies possessed by the surface of the earth or present in the earth’s atmosphere, without active addition of thermal or other energy forms. The term encompasses any and all forms of energies, including, but not limited to, electromagnetic energy, solar energy, radiant energy, thermal energy, or a combination thereof.

As used herein, the term “ambient temperature” refers to a temperature of the earth’s atmosphere. In some embodiments, ambient temperature ranges from about 5? to about 65?.

As used herein, the term “impregnation” or “impregnated” refers to soaking, saturation, coating, or infusion of rGO or source comprising rGO with an alkali.

The inventors have found that carbonaceous materials could be oxidized by aerial oxygen in presence of an electrolyte under atmospheric conditions to generate electricity. In particular, the inventors have found that reduced graphene oxide (rGO) present in carbonaceous materials like coal can react with oxygen in the presence of ambient energy in the earth’s atmosphere to generate electricity at the ambient temperatures.

The present disclosure provides a method for producing electricity that mimics the redox cycle of aerobic respiration in mammals. In particular, the present inventors have found that the specific carbon containing compound viz. reduced graphene oxide (rGO) present in carbonaceous materials like coal can be oxidized by reacting with oxygen in presence of ambient energy and an electrolyte such as an alkali to produce electricity. In this method, reduction and oxidation of oxygen is coupled with reduction and oxidation of reduced graphene oxide to generate electricity. This process involving the rGO/GO and oxygen cycles in presence of ambient energy and electrolyte is presented in Scheme 1.

Scheme 1
The first step in this composite cycle is the interaction of rGO with triplet oxygen (aerial or pure) under ambient energy to produce {rGO*||3O2} as a first adduct. This step activates oxygen to its singlet state to produce a second adduct, {rGO+||1O2-}. The second adduct participates in electron transfer to generate the charge transfer exciton, {rGO+||O2-}. Strong base like NaOH has been used to increase the lifetime of O2-. The second adduct in presence of a hydroxide (OH-) radical produces a HO2- radical and a {rGO+OH-} adduct. The {rGO+OH-} adduct reacts with the HO2- radical to produce graphene oxide (GO), a formate ion (HCO2-), and a carbonate ion (CO32-). The GO in the presence of the ambient energy and a OH- radical regenerates the rGO to complete the cycle. The redox steps of aerial oxygen on reacting with rGO under ambient energy forming singlet oxygen, superoxide and finally hydroperoxide ion have been experimentally verified as described in the examples below.

After the first cycle, the regenerated rGO participates in the next cycle. This cycle would continue so long rGO or oxygen is not exhausted. The two redox processes involved here are dioxygen-singlet oxygen-superoxide-peroxide redox cycle coupled with rGO/ GO cycle. This entire process is shown in the above Scheme 1. Thus, one can build ambient energy harvesting system by coupling rGO/GO redox cycle with a redox cycle of oxygen to produce electrical energy in an efficient and economical manner.

Accordingly, the present disclosure provides a method for producing electrical energy comprising reacting reduced graphene oxide (rGO) with oxygen in presence of ambient energy, wherein the rGO is impregnated with an alkali.

In an embodiment, the rGO is in pure form, or a source comprising rGO, or a combination thereof. rGO is naturally present in carbonaceous materials like coal. Accordingly, in some embodiments, a source comprising rGO is a carbonaceous material. In some embodiments, a carbonaceous material comprising rGO includes charred grass, charred dry leaves, charred wood charcoal, and coal. In some embodiments, a source comprising rGO is soot obtained by burning a vegetable or mineral oil. In some embodiments, a source comprising rGO is an exhaust or soot generated by combustion of fuel such as exhaust from automobiles or soot collected from chimneys.

In some embodiments, a source comprising rGO is coal. In some embodiments, coal comprising rGO can be a low-grade coal to a high-grade coal including lignite, sub-bituminous coal, bituminous coal and anthracite coal.

In some embodiments, coal employed in the methods and cells of the invention is selected from the group consisting of sub-bituminous coal, bituminous coal, anthracite coal, coking coal, non-coking coal, and any combination thereof. In some embodiments, any grade of coking coal can be employed. In some embodiments, Grades I-IV of coking coal are employed. In some embodiments, non-coking coal of Grades A to G is used. In some embodiments, the coal is first oxidized to increase the content of rGO and then employed in the methods and products of the disclosure.

In an embodiment of the present disclosure, oxygen that reacts with rGO can be pure oxygen, aerial oxygen, or a combination thereof.

The reaction of rGO with oxygen takes place in presence of ambient energy. Various forms of energies are naturally present in the earth’s atmosphere. As noted above, the term “ambient energy” refers to these forms of energies which include, but are not limited to, electromagnetic energy, solar energy, radiant energy, thermal energy, or a combination thereof. It is noted that no source of energy (thermal or otherwise) is actively provided for the reaction of rGO with oxygen to take place.

In some embodiments, the reaction of rGO with oxygen takes place in presence of electromagnetic energy. In some embodiments, the reaction of rGO with oxygen takes place in presence of solar energy. In some embodiments, the reaction of rGO with oxygen takes place in presence of radiant energy. In some embodiments, radiant energy comprises radiations having a wavelength ranging from about 100 nm to about 2500 nm. In some embodiments, radiant energy comprises cosmic radiations on the surface of the earth. In some embodiments, the reaction of rGO with oxygen takes place in presence of thermal energy. In some embodiments, the reaction of rGO with oxygen takes place in presence of global warming of the earth’s atmosphere. In this embodiment, global warming of the earth’s atmosphere is a form of ambient energy. In some embodiments, the reaction of rGO with oxygen takes place in presence of a combination of any of these energies.

In an embodiment of the present disclosure, in the reaction of rGO with oxygen, rGO is impregnated with an alkali. In some embodiments, the alkali maintains a pH of at least 12. In some embodiments, the alkali maintains a pH of about 12 or more. In some embodiments, the alkali maintains a pH of about 12 to about 14. In some embodiments, the alkali maintains a pH of about 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, or 14.

The pH of 12 or more helps in: i) increasing the stability of a superoxide anion and thus, increases the life of the exciton with spatial separation between the electron and hole, and ii) generating the potent oxidant HO2- radical. The hydroperoxide oxidation of rGO+ involves a moulting process where rGO’s peripheral carbonyl groups are removed in the form of carbonate and formate to complete the cycle. The inventors have quantified the extrusion of peripheral carbons, present as carbonyl groups in rGO, in the form of carbonate and formate. In an embodiment, a mass loss of carbon to the tune of about 5% has been measured when a cell in accordance with the invention was run for 30 days, day and night. In one embodiment, the overall redox potential of such a system has been measured around 0.430 mV at 25?, which slightly varies with temperature.

In some embodiments, the alkali is an alkali solution having a concentration of at least 1M. In some embodiments, the alkali solution has a concentration of about 1M or more. In some embodiments, the alkali solution has a concentration of about 1M, about 1.25M, about 1.5M, about 1.75M, about 2M, about 2.25M, about 2.5M, about 2.75M, about 3M, about 3.25M, about 3.5M, about 3.75M, or about 4M, including values and ranges thereof. In some embodiments, the alkali solution has a concentration of about 1M to about 4M.

In some embodiments, the amount of alkali is about 10% to about 25%, including all values and ranges therebetween, by weight of the total weight of the rGO or the source containing rGO and the alkali. In some embodiments, the amount of alkali is about 10%, about 15%, about 20%, or about 25% by weight of the total weight of the rGO or the source containing rGO and the alkali.

In some embodiments, the alkali is an alkali or alkaline earth metal oxide; alkali or alkaline earth metal hydroxide; alkali or alkaline earth metal carbonates; quaternary ammonium hydroxides or carbonates such as tetraalkyl ammonium hydroxide, tetraaryl ammonium hydroxide, tetraalkyl ammonium carbonate; asymmetric tetraalkyl ammonium salt; or asymmetric tetraalkyl phosphonium salt, alone or a combination thereof, or in combination with a neutral electrolyte. In some embodiments, alkali metal oxides include lithium oxide, sodium oxide, potassium oxide, rubidium oxide, and caesium oxide. In some embodiments, alkaline earth metal oxides include beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, and radium oxide. In some embodiments, alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and caesium hydroxide. In some embodiments, alkaline earth metal hydroxides include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, and radium hydroxide. In some embodiments, tetraalkyl ammonium hydroxides include tetramethyl ammonium hydroxide, tetrabutyl ammonium hydroxide, and the like. In some embodiments, tetraaryl ammonium hydroxides include tetraphenyl ammonium hydroxide and the like. In some embodiments, alkali metal carbonates include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and caesium carbonate. In some embodiments, alkaline earth metal carbonates include beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate. In some embodiments, tetraalkyl ammonium carbonates include tetramethyl ammonium carbonate, tetrabutyl ammonium hydroxide, and the like. In some embodiments, the alkali is an asymmetric tetraalkyl ammonium salt such as a cetyltrialkyl ammonium salt. In some embodiments, the alkali is an asymmetric tetraalkyl phosphonium salt. In some embodiments, a combination of these alkalis is used. In some embodiments, any of these alkalis are used in combination with a neutral electrolyte.

In some embodiments, the alkali is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and combinations thereof. In some embodiments, any of these alkalis are used in combination with a neutral electrolyte.

It will be understood by a person of ordinary skill in the art that any of the above-mentioned alkalis can be employed to impregnate rGO at any of the concentrations, pH values and weight percentages mentioned above.

In some embodiments, the method of the present disclosure is carried out at an ambient temperature. As defined above, the term “ambient temperature” refers to a temperature of the earth’s atmosphere. In some embodiments, the ambient temperature is the temperature of surroundings. In some embodiments, the ambient temperature is room temperature. In some embodiments, ambient temperature ranges from about 5? to about 65?, about 5? to about 60?, about 5? to about 55?, about 5? to about 50?, about 5? to about 45?, about 5? to about 40?, about 10? to about 65?, about 10? to about 60?, about 10? to about 55?, about 10? to about 50?, about 10? to about 45?, about 10? to about 40?, about 15? to about 65?, about 15? to about 60?, about 15? to about 55?, about 15? to about 50?, about 15? to about 45?, about 15? to about 40?, about 20? to about 65?, about 20? to about 60?, about 20? to about 55?, about 20? to about 50?, about 20? to about 45?, about 20? to about 40?, about 20? to about 35?, about 20? to about 30?, about 25? to about 65?, about 25? to about 60?, about 25? to about 55?, about 25? to about 50?, about 25? to about 45?, about 25? to about 40?, about 25? to about 35?, about 25? to about 30?, about 30? to about 65?, about 30? to about 60?, about 30? to about 55?, about 30? to about 50?, about 30? to about 45?, about 30? to about 40?, or about 35? to about 45?, including all values and ranges thereof. In some embodiments, the ambient temperature is about 5?, about 10?, about 15?, about 20?, about 25?, about 30?, about 35?, about 40?, about 45?, about 50?, about 55?, or about 65?. The current invention does not require any external source of heat as it works well at ambient temperature however this cannot be construed as limitation since the current process can work well beyond 65? as well. In some embodiments, the ambient temperature is more than 65?, for example, up to about 200?. For example, in some embodiments, the ambient temperature is about 70?, 75?, 80?, 85?, 90?, 95?, 100?, 105?, 110?, 115?, 120?, 125?, 130?, 135?, 140?, 145?, 150?, 155?, 160?, 165?, 170?, 175?, 180?, 185?, 190?, 195?, or 200?.

In an embodiment, the methods described above provide a voltage of about 450 mV and a current of about 2 mA from one unit of 500 mg coal (GO/rGO) cell. In another embodiment, a pure 50 mg of GO/rGO sample isolated from coal generates about 6 mA current and a voltage of about 460 mV.

The present disclosure also provides an electrochemical cell that employs the method described above to produce electrical energy or electricity. In some embodiments, the cell comprises: (a) an anode comprising reduced graphene oxide (rGO), wherein the rGO is impregnated with an alkali solution; (b) means for introducing oxygen into the cell; and (a) a cathode.

In the cell, rGO impregnated with an alkali solution acts as an anode. In an embodiment, the rGO is in pure form, or a source comprising rGO, or a combination thereof. rGO is naturally present in carbonaceous materials like coal. Accordingly, in some embodiments, a source comprising rGO is a carbonaceous material. In some embodiments, a source comprising rGO is coal.

In some embodiments, coal comprising rGO can be a low-grade coal to a high-grade coal including lignite, sub-bituminous coal, bituminous coal and anthracite coal.

In some embodiments, coal employed in the cells of the invention is selected from the group consisting of sub-bituminous coal, bituminous coal, anthracite coal, coking coal, non-coking coal, and any combination thereof. In some embodiments, any grade of coking coal can be employed. In some embodiments, Grades I-IV of coking coal are employed. In some embodiments, non-coking coal of Grades A to G is used. In some embodiments, the coal is first oxidized to increase the content of rGO and then employed in the cells of the disclosure.

In some embodiments, the alkali solution is a solution of an alkali or alkaline earth metal oxide; a solution of alkali or alkaline earth metal hydroxide; a solution of alkali or alkaline earth metal carbonates; a solution of a quaternary ammonium hydroxide or carbonate such as a solution of tetraalkyl ammonium hydroxide, a solution of tetraaryl ammonium hydroxide, a solution of tetraalkyl ammonium carbonate; a solution of asymmetric tetraalkyl ammonium salt or a solution of asymmetric tetraalkyl phosphonium salt, alone or a combination thereof or in combination with other neutral electrolyte. In some embodiments, alkali metal oxides include lithium oxide, sodium oxide, potassium oxide, rubidium oxide, and caesium oxide. In some embodiments, alkaline earth metal oxides include beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, and radium oxide. In some embodiments, alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and caesium hydroxide. In some embodiments, alkaline earth metal hydroxides include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, and radium hydroxide. In some embodiments, tetraalkyl ammonium hydroxides include tetramethyl ammonium hydroxide, tetrabutyl ammonium hydroxide, and the like. In some embodiments, tetraaryl ammonium hydroxides include tetraphenyl ammonium hydroxide and the like. In some embodiments, alkali metal carbonates include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and caesium carbonate. In some embodiments, alkaline earth metal carbonates include beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate. In some embodiments, tetraalkyl ammonium carbonates include tetramethyl ammonium carbonate, tetrabutyl ammonium hydroxide, and the like. In some embodiments, the alkali solution is a solution of an asymmetric tetraalkyl ammonium salt such as a solution of cetyltrialkyl ammonium salt. In some embodiments, the alkali solution is a solution of an asymmetric tetraalkyl phosphonium salt. In some embodiments, a combination of these alkalis is used. In some embodiments, any of these alkali solutions are used in combination with a neutral electrolyte.

In some embodiments, the alkali solution is selected from the group consisting of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, potassium carbonate solution, and combinations thereof. In some embodiments, any of these alkali solutions are used in combination with a neutral electrolyte.

In some embodiments, the alkali solution maintains a pH of at least 12. In some embodiments, the alkali solution maintains a pH of about 12 or more. In some embodiments, the alkali solution maintains a pH of about 12 to about 14. In some embodiments, the alkali solution maintains a pH of about 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, or 14.

In some embodiments, the alkali solution has a concentration of at least 1M. In some embodiments, the alkali solution has a concentration of about 1M or more. In some embodiments, the alkali solution has a concentration of about 1M, about 1.25M, about 1.5M, about 1.75M, about 2M, about 2.25M, about 2.5M, about 2.75M, about 3M, about 3.25M, about 3.5M, about 3.75M, or about 4M, including values and ranges thereof. In some embodiments, the alkali solution has a concentration of about 1M to about 4M.

In some embodiments, the amount of alkali solution is about 10% to about 25%, including all values and ranges therebetween, by weight of the total weight of the rGO or the source containing rGO and the alkali solution. In some embodiments, the amount of alkali solution is about 10%, about 15%, about 20%, or about 25% by weight of the total weight of the rGO or the source containing rGO and the alkali solution.

The alkali solution employed in the cell is a solution comprising any of the above-mentioned alkalis at any of the concentration and pH values mentioned above and present at any of the weight percentages mentioned above.

The cell comprises means for introducing oxygen or air into the cell allowing oxygen to react with rGO and the oxygen is introduced into the cell by any means. In one embodiment, the means for introducing oxygen into the cell comprise one or more pores made into the cell. In this disclosure, the terms “pores”, “perforations”, “holes” could be used interchangeably to refer to the openings made into the cell to allow passage of oxygen, pure or aerial. One of ordinary skill in the art would understand that in this embodiment, oxygen is introduced into the cell passively, i.e., entry of oxygen is not under pressure.

In one embodiment, the cathode comprises graphite. In some embodiments, cathode comprises a noble metal. In some embodiments, the noble metal is platinum, gold, or a combination thereof.

The anode and the cathode of the cell are connected by a conductive material. For example, the anode and the cathode are connected by metallic connectors or wires comprising a conductive material. In some embodiments, said conductive material is selected from the group consisting of copper, aluminum, tin, iron, nickel, cobalt, silver, platinum, gold, any noble metal, and combinations thereof.
In the cell, the direction of the flow of electrons is from anode/rGO (negative) to cathode (positive).

In an embodiment, one end of one of the conductive materials (metallic connectors) is connected to the anode (rGO) and one end of the other conductive material is connected to the cathode. The other ends of the conductive materials can be connected to a load to be powered from the cell. When such connection is made, there exists an electrical path for the electrons to flow from the anode/rGO via the conductive material and the load to the cathode. Thus, the electrons flow through the electrical path powering the load. Hence, the cell of the present disclosure works like a conventional cell configured to power a load. In an embodiment, the load may have positive and negative terminals and the terminals of the load can be connected to the anode/rGO and the cathode, respectively. For example, in one embodiment, an Light Emitting Diode (LED) can be connected to the cell. The LED can have a positive terminal and a negative terminal. The positive terminal of the LED can be connected to the cathode and the negative terminal of the LED can be connected to the anode/rGO. When such a connection is made, the LED glows due to the flow of electrons from the rGO via the LED and to the cathode. In a similar embodiment, a motor powering a fan can be connected to the cell. In an embodiment, a plurality of cells can be connected in parallel to enable maximum current to flow through the load. In another embodiment, a plurality of cells can be connected in series to maintain a constant current and resultant voltage supplied to the load is a sum of voltage of each cell.

In an embodiment, as the cell continues to run, sodium ions (or potassium ions or the corresponding metal ions of the alkali used in the cell) change to the corresponding formate salt which gets deposited in the cell reducing the efficiency of the cell. Deposits of formate salts need to be removed as well as fresh supply of alkali needs to be provided to the cell. In some embodiment, deposits of formate salts can be removed by simply washing the cell with water and the cell can be recharged with a fresh alkali solution. The washed solution containing dissolved formate salt on evaporation can yield solid residue of the formate salt, which is a valuable by-product. In one embodiment, to make the process of washing and recharging the cell with an alkali solution, the cell attachment is modular in a cartridge form whereby the old (used) cell is readily exchanged with a new one and the old cell is regenerated by proper washing and refilling with alkali.

In an embodiment, the amount of electric current generated by the cell increases as the surface area of rGO or the thickness or layers of rGO increases until the diffusion of oxygen through rGO is no longer possible. This is further exemplified in Example 3 of the present disclosure. FIG. 3A shows that the electric current increases as the number of layers of coal comprising rGO increases. However, the current does not increase after a certain number of layers of coal, as the diffusion of oxygen through the increasing number of layers is no longer possible. FIG. 3B further shows that the current increases as the surface area of rGO increases.

In some embodiments of the cell, rGO is present in the form of layers and each layer has a thickness ranging from about 0.1 mm to 0.3 mm (100µ to 300µ), including all values and ranges therebetween. In some embodiments, each layer of rGO has a thickness of about 100µ, about 125µ, about 150µ, about 175µ, about 200µ, about 225µ, about 250µ, about 275µ, or about 300µ.

One of ordinary skill in the art would understand that the cell can be constructed in any shape. For example, in some embodiments, the cell can be of a rectangular shape, square shape, circular shape, oval shape, cylindrical shape, cube shape, cuboid shape, sheet type, a collective sheet type forming a book of different sizes, and the likes.

In an embodiment, the cell is constructed from any suitable material. For example, in one embodiment, the cell is constructed of a plastic material. In some embodiments, the plastic material is selected from the group consisting of polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyamide, polyester, polyurethane, and a combination thereof.

The present disclosure also provides systems comprising a plurality of cells. Each of said cells comprises features as described above. In such systems, the plurality of cells can be connected in various configurations. For example, in some embodiments, the plurality of cells are connected in series. In some other embodiments, the plurality of cells are connected in parallel. In yet some other embodiments of the system, a first plurality of cells are connected in series, a second plurality of cells are connected in parallel, and the first and the second plurality of cells are connected in series or in parallel. Various such configurations can be envisaged by one of ordinary skill in the art and are encompassed by the present disclosure. Figures 11B, 11C, 12, and 13 show exemplary embodiments of systems comprising a plurality of cells in various configurations encompassed by the present disclosure.

The methods, cells, and systems disclosed herein provide many advantages. Firstly, the present methods, cells, and systems are environmental-friendly and contribute to the field of green technology. In particular, the disclosure provides for very low-cost, energy efficient and green energy employed methods, cells, and systems for generating electricity. For example, electrical energy is generated by harnessing ambient energy present in the surroundings of the cell and no separate/actively added energy source is required for the functioning of the methods, cells, and systems of the present disclosure. This saves costs and resources required for providing a separate energy source. This is in contrast to the Jacques’ patent mentioned above, where an iron pot (cathode) comprising a carbon rod (anode), an electrolyte, and an air pump for introducing air under pressure is placed inside a furnace that keeps the temperature at 400? to 500? (see page 2, left column, lines 25-28 of the Jacques patent). Thus, in the Jacques method, introduction of air under pressure as fine sprays and a separate energy source in the form of a furnace maintained at 400? to 500? are required to generate electricity whereas in the present method, any form of ambient energy present in the atmosphere surrounding the cell or system is sufficient to generate electricity.

The present methods, cells and systems are also advantageous over conventional methods for generating electricity such as methods involving combustion of coal (which requires fuel and high temperature burning for combustion and contributes to air pollution), solar-powered cells (high cost of silicon-based raw material, availability of sunlight), etc. Moreover, the present simple ambient energy induced rGO-oxygen reaction allows to produce electrical energy that is operative day and night as well as indoors and outdoors.

The methods, cells, and systems of the present disclosure are operated at an ambient temperature, i.e., the temperature of the atmosphere surrounding the cell. While the amount of current produced varies with the temperature surrounding the cell, such variations can be mitigated by connecting a plurality of cells in series, in parallel, or a combination thereof.

It is to be understood that the foregoing descriptive matter is illustrative of the disclosure and not a limitation. While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. Similarly, additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein.

Descriptions of well-known/conventional methods/steps and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for examples illustrating the above described embodiments, and in order to illustrate the embodiments of the present disclosure certain aspects have been employed. The examples used herein for such illustration are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES

Example 1: Oxygen for generation of electricity
A cell was constructed by placing sub-bituminous coal containing 8% by weight of reduced graphene oxide (rGO) (anode) in a perforated (allowing air to pass) polypropylene container with graphite (cathode) at the bottom. The coal was impregnated with saturated NaOH solution. A copper wire was placed in the coal impregnated with NaOH and a second copper wire was connected to the graphite. The copper wires act as terminals and the ends of the copper wires were connected to a LED bulb. Two such cells were constructed and placed inside small Erlenmeyer flasks. The mouth of the two flasks were properly sealed with septum and glue.

When both the conical flasks were allowed to flow normal air, a potential of about 450 mV was observed across the two terminals of the cells. In contrast, when the two flasks were purged with an inert gas such as argon, a very small potential was observed (small potential was due to traces of air present in the flask). Figure 1 demonstrates this oxygen dependency of the reaction. The LED bulb did not glow when the flask was pre-purged with argon. However, when the argon inside the flask was flushed out by fresh air, the LED bulb started to re-glow with the in-flow of oxygen. Carbon dioxide and formic acid formed in this process due to the reaction between hydroperoxide (a product of oxygen cycle) and carbonyl groups of rGO was quantified as trapped in NaOH forming carbonate and formate.

Example 2: Temperature dependency of voltage and current
To understand the effect of temperature on voltage and current, the cell was constructed as described in Example 1. The temperature was varied from 5? to 65? and the hysteresis plots shown in Figures 2A and 2B were generated. A hysteresis plot is generated based on a heating cycle and a cooling cycle in the given temperature range (5-65?). Two such consecutive cycles result in four readings at a given temperature. The purpose of plotting hysteresis plots is to see if there is a lag between input and output in a system upon a change in direction. Voltage showed a smaller variation as the temperature of the surrounding changes (Figure 2A), whereas current showed a larger variation with the temperature (Figure 2B). Voltage changed from about 420-470 mV as the temperature changed from 5? to 65?. Current showed a larger variation like 0.5 to 6 mA in this temperature range. However, low energy experiments were conducted under a fridge where all other energy sources were cut. In both the forward and reverse steps of the redox reactions and from the first cycle to the second cycle of the reactions, not much variation in current or voltage was noticed. Variations observed in the temperature range (Figures 2A-2B) are due to kinetic and thermodynamic dependency of these reactions as shown in Scheme 1. A prototype of a system comprising coal-based rGO cells connected in series or in parallel and generating electricity day and night (absence of sunlight) to light an LED bulb or drive a DC motor for days is shown in Figures 3A and 3B. The cells were made up of a polypropylene container having several holes to allow air and were placed inside a room with an average temperature of 25?.

Example 3: Current increases with the thickness and surface area of rGO
The spread of the coal layers comprising rGO was calculated based on the amount of coal spread over a given surface area. Based on this, an approximate number of layers of the coal and the thickness of the layers were calculated. It was determined that the thickness of approximately three to four layers was about 0.5 mm. As shown in Figure 4A, the current increased with the number of layers of coal comprising rGO. However, after 15 layers (5 mg mass spread over 1 cm2 area), the current value did not change. The current did not increase after 15 layers of coal, as air could not diffuse further through the layers. Figure 4B shows that the current increases as the surface area of coal containing rGO increases.

Example 4: Construction of an exemplary cell
A polypropylene container having 4.5 cm diameter and 1 cm height with lots of pores on its surface to pass air was prepared. A circular graphite sheet (0.25 mm thick) (cathode) connected with a copper wire (metallic connector) was placed at its bottom. Powdered low-grade coal (anode) washed by acetone and hydrochloric acid (2.5g) was placed on the graphite sheet inside the container and a copper wire (metallic connector) was placed on the top to function as an electrode. This coal powder was impregnated with saturated NaOH solution to constitute a cell. Such cells were also constructed in an Eppendorf vial where the amount of coal taken was 0.5 g.

Example 5: Radiant energy for generation of electricity
Cells were constructed as described in Example 4. Groups of cells were placed inside different colored transparent sheets (the sheets acted as colored filters), as shown in Figure 5. In Figure 5, top row shows cells covered with red, yellow, or blue colored transparent sheets from left to right; middle row shows cells covered with green colored transparent sheet and white transparent sheets from left to right; and the last row shows cells covered with a black sheet. It was observed that the red colored transparent sheet was the most effective in generating the potential across the terminals. As the red part of the light comprises more proportion of heat-generating wavelengths (such as infra-red wavelengths) than visible wavelengths, the most effective generation of potential using the red filter indicates that radiant energy (heat energy) was responsible for the generation of potential. It was observed that the potential across the terminals was not affected by visible light. Even covering the cells with a black sheet, no changes to the potential were observed indicating that ambient energy such as radiant energy was responsible for the generation of potential. This is unlike silicon based solar cells which require visible light for its efficiency.

Example 6: Generation of intermediates and by-products
In the method of the present disclosure, i.e. reaction for producing electrical energy by reacting rGO with oxygen in presence of ambient energy, wherein the rGO is impregnated with an alkali, several intermediates and by-products are formed as follows:

Detection of formate: The concentration of formic acid produced from the cell reaction was measured by measuring the amount of formate. For this, a pre-determined amount of rGO was taken in a test tube containing 50% aqueous NaOH solution (10 mL). Fresh air, freed from atmospheric carbon dioxide and other environmental gases by bubbling through 3 M hydrochloric acid followed by 10% sodium hydroxide, was allowed to bubble through the NaOH solution containing rGO for 10 days using an aquarium pump. The reaction mixture was transferred in a three necked flask and 4M H2SO4 was added drop wise to it. After the addition of H2SO4, the volume of acidified mixture was made to 200 ml and this was centrifuged. Into a 2 ml aliquot of the supernatant, 2 ml 6 N HCl was added and portion wise little Mg powder was added into it till it dissolved with effervescence. 0.5 ml freshly prepared chromotropic acid was added to it and the resultant violet color solution was subjected to electronic spectral measurement at 570 nm. Figure 6A shows the spectrophotometric measurement of formic acid. The amount of formate was calculated from the standard calibration curve of sodium formate using Lambert-Beer’s law as shown in Figure 6B. Only ~2 % of rGO was consumed for 30 hours reaction.

Detection of superoxide radicals: 50 mg coal wrapped in a Whatman filter paper was immersed in a test tube containing water and was made lukewarm. A part of NBT test solution was added on to it. After few minutes, a little DCM was added to it and the test tube was shaken vigorously and finally allowed to settle. Aqueous and DCM layers were separated. The DCM phase showed characteristic blue color (?max = 588 nm) of formazan formed by superoxide. In the presence of sodium azide, this reaction did not take place indicating that sodium azide inhibited generation of superoxide ions.

Detection of peroxide: In a round Whatman filter paper, soaked in potassium iodide (KI) solution and dried in air, 10 mg of coal (in paste form with saturated NaOH) was placed in the center. A blank without coal but with NaOH was used as a control. Within few minutes, deep brown coloration was developed circling the coal mass, which when leached with DCM, showed characteristic violet color of iodine. No coloration developed on the control filter paper.

Figure 6C shows the yellow brown coloration developed around the coal mass. The peroxide generated during the oxidation of rGO in the presence of alkali oxidizes potassium iodide (KI) to iodine (I2) which diffuses through the filter paper imparting yellow brown color.

Example 7: Preparation/Isolation of rGO from coal
Coal contains naturally formed GO and rGO. In this experiment, coal was purified to remove impurities; naturally occurring rGO was converted to GO using a nitric acid treatment; GO was extracted using an alkali and converted to rGO.
Purification of low-grade coal: Low grade coal in powdered form was first freed from aromatic hydrocarbons and other soluble organic compounds by repeatedly washing with acetone, using Soxhlet extractor. It was then treated with 6M hydrochloric acid repeatedly for 7 days to free it from soluble inorganic oxides and finally washed it by water and dried in air. About 8% of the naturally occurred GO present there can be leached out by treating this with alkali and re-precipitating by addition of an acid. The amount of GO can be further increased by a subsequent nitric acid treatment. Figures 7A-7C show the FT-IR spectrum, Raman spectrum, and the X-ray diffraction pattern and Figure 7D shows the transmission electron micrograph (TEM) of the rGO present in the coal.

Isolation of GO: As the purified coal contains large amount of rGO, the dried powdered coal (10.0 g) was treated with concentrated nitric acid (250 mL) in portion (to avoid excessive heat generation) to oxidize rGO to GO and allowed to stand overnight at room temperature. The slurry was evaporated to dryness in boiling water bath and finally the mass was dried under vacuum using solid NaOH as a desiccating agent, to remove the residual nitric acid to yield a yellow-brown solid. This solid was dissolved in 10% sodium hydroxide solution to get a yellow–brown solution and this was centrifuged and the centrifugate was neutralized with dilute hydrochloric acid to pH 7 which on standing a brown flaky precipitate of GO appeared. This precipitate was separated out by centrifugation, washed with cold water to free it from sodium chloride formed in the neutralization process and finally dried in air yielding a red brown solid with almost 90 % yield based on the weight of the coal. The method is slightly modified as described in RSC. Adv., 2015, 05, 89076-89082. Figures 8A-8C show the FT-IR spectrum, Raman spectrum, and the X-ray diffraction pattern and Figure 8D shows the transmission electron micrograph (TEM) of the isolated GO.

Preparation of reduced GO (rGO): A suspension of GO was treated with hypophosphorous acid wherein the brown color GO is changed to black mass containing rGO. This was centrifuged and washed with fresh water repeatedly to make it acid free. Figures 9A-9Cshow the FT-IR spectrum, Raman spectrum, and the X-ray diffraction pattern and Figure 9D shows the transmission electron micrograph (TEM) of the rGO.

The FT-IR spectra, Raman spectra, and the X-ray diffraction patterns from Figures 7, 8, and 9 show the characteristic signature of rGO indicating that rGO is naturally present in coal. The TEM for each sample visually shows the morphology of these samples and indicates that the samples comprise nano carbon domain retaining graphitic structures.

Recovered GO after cell reaction:
A few hours after the cell reaction was carried out, the remaining material was washed and subjected to similar X-ray diffraction, IR, RAMAN spectroscopy and TEM. Figures 10A-10Cshow the FT-IR spectrum, Raman spectrum, and the X-ray diffraction pattern and Figure 10D shows the transmission electron micrograph (TEM) of the recovered GO after few hours of cell reaction. Figure 10 shows that the rGO is still present and the cell can be further operated.

Physical measurements: In the Examples described above, electronic spectral measurements were carried out with JASCO, V-630 spectrophotometer while pH of the solution was monitored using LABMAN Benchtop pH Meter. FTIR and Raman spectra were recorded using JASCO FT/IR-4000 Series machine using KBr disk and LabRam HR 800 Raman Spectrometer respectively. The powder X-ray diffraction data were collected on a Bruker D8 Advance X-ray diffractometer using Cu Ka radiation (?= 1.5418 Å) generated at 40 kV and 40 mA. TEM images were taken on FEI, TECHNAI-T-20 machine attached with EDAX operated on the voltage at 200 kV. Electrochemical measurements were carried out with BioLogic SP-150 Potentiostats/Galvanostats.

INCORPORATION BY REFERENCE
All references, articles, publications, patents, patent publications, and patent applications cited herein are incorporated by reference in their entireties for all purposes. However, mention of any reference, article, publication, patent, patent publication, and patent application cited herein is not, and should not be taken as, an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.

Claims:We Claim:
1. A method for producing electrical energy comprising reacting reduced graphene oxide (rGO) with oxygen in presence of ambient energy, wherein the rGO is impregnated with alkali.
2. The method as claimed in claim 1, wherein the rGO is pure rGO or a source comprising rGO, or a combination thereof.
3. The method as claimed in claim 2, wherein the source is a carbonaceous material.
4. The method as claimed in claim 3, wherein the carbonaceous material is coal.
5. The method as claimed in claim 4, wherein the coal is a low-grade coal or a high-grade coal.
6. The method as claimed in claim 4, wherein the coal is selected from the group consisting of sub-bituminous coal, bituminous coal, anthracite coal, non-coking coal, coking coal, and any combination thereof.
7. The method as claimed in claim 4, wherein the coal is oxidized to produce rGO.
8. The method as claimed in claim 1, wherein the oxygen is aerial oxygen or pure oxygen.
9. The method as claimed in claim 1, wherein the ambient energy is selected from the group consisting of electromagnetic energy, solar energy, radiant energy, thermal energy, and combinations thereof.
10. The method as claimed in claim 1, wherein the ambient energy is electromagnetic energy.
11. The method as claimed in claim 1, wherein the ambient energy is solar energy.
12. The method as claimed in claim 1, wherein the ambient energy is radiant energy.
13. The method as claimed in claim 1, wherein the ambient energy is thermal energy.
14. The method as claimed in claim 1, wherein the alkali is selected from the group consisting of an alkali metal oxide, an alkaline earth metal oxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkali metal carbonate, an alkaline earth metal carbonate, a tetraalkyl ammonium hydroxide, a tetraalkyl ammonium carbonate, a tetraaryl ammonium hydroxide, asymmetric tetraalkyl ammonium salt, asymmetric tetraalkyl phosphonium salt and combinations thereof.
15. The method as claimed in claim 14, wherein the alkali is present in combination with a neutral electrolyte.
16. The method as claimed in claim 14, wherein the alkali is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, an asymmetric cetyltrialkyl ammonium salt, an asymmetric cetyltrialkyl phosphonium salt, and combinations thereof.
17. The method as claimed in claim 1, wherein the alkali maintains a pH of at least 12.
18. The method as claimed in claim 1, wherein the alkali is an alkali solution having a concentration of at least 1M.
19. The method as claimed in claim 1, wherein the method is carried out at an ambient temperature.
20. The method as claimed in claim 1, wherein the method comprises a continuous dioxygen-superoxide-peroxide redox cycle coupled with a rGO/GO cycle.
21. The method as claimed in claim 1, wherein:
the rGO reacts with the oxygen in the presence of the ambient energy to produce {rGO* ||3O2} as a first adduct;
the first adduct is converted into {rGO+ ||1O2-} as a second adduct;
the second adduct in presence of a hydroxide (OH-) radical produces a HO2-radical and a {rGO+OH-} adduct;
the {rGO+OH-} adduct reacts with the HO2- radical to produce graphene oxide (GO), a formate ion (HCO2-), and a carbonate ion; and
the GO in the presence of the ambient energy and a OH- radical regenerates the rGO.
22. A cell comprising:
a. an anode comprising reduced graphene oxide (rGO), wherein the rGO is impregnated with an alkali solution;
b. means for introducing oxygen into the cell; and
c. a cathode.
23. The cell as claimed in claim 22, wherein the cathode comprises graphite.
24. The cell as claimed in claim 22, wherein the cathode comprises a noble metal.
25. The cell as claimed in claim 24, wherein the noble metal is selected from platinum and gold.
26. The cell as claimed in claim 22, wherein one of the means for introducing oxygen into the cell comprises perforations made in the cell.
27. The cell as claimed in claim 22, wherein the anode and the cathode are connected by a conductive material, wherein said conductive material is selected from the group consisting of copper, aluminum, tin, iron, nickel, cobalt, silver, platinum, gold, any noble metal, and combinations thereof.
28. The cell as claimed in claim 22, wherein the rGO is pure rGO or a source comprising rGO.
29. The cell as claimed in claim 28, wherein the source is carbonaceous material.
30. The cell as claimed in claim 29, wherein the carbonaceous material is coal.
31. The cell as claimed in claim 30, wherein the coal is a low-grade coal or a high-grade coal.
32. The cell as claimed in claim 30, wherein the coal is selected from the group consisting of sub-bituminous coal, bituminous coal, anthracite coal, coking coal, non-coking coal, and any combination thereof.
33. The cell as claimed in claim 30, wherein the coal is oxidized to produce rGO.
34. The cell as claimed in claim 22, wherein the oxygen is aerial oxygen or pure oxygen, or a combination thereof.
35. The cell as claimed in claim 22, wherein the alkali solution is selected from the group consisting of a solution of an alkali metal oxide, a solution of an alkaline earth metal oxide, a solution of an alkali metal hydroxide, a solution of an alkaline earth metal hydroxide, a solution of an alkali metal carbonate, a solution of an alkaline earth metal carbonate, a solution of a tetraalkylammonium hydroxide, a solution of a tetraalkylammonium carbonate, a solution of a tetraaryl ammonium hydroxide, a solution of an asymmetric tetraalkyl ammonium salt, a solution of an asymmetric tetraalkyl phosphonium salt, and combinations thereof.
36. The cell as claimed in claim 35, wherein the alkali solution is present in combination with a solution of a neutral electrolyte.
37. The cell as claimed in claim 35, wherein the alkali solution is selected from the group consisting of a sodium hydroxide solution, a potassium hydroxide solution, a sodium carbonate solution, a potassium carbonate solution, an asymmetric cetyltrialkyl ammonium salt solution, an asymmetric cetyltrialkyl phosphonium salt solution and combinations thereof.
38. The cell as claimed in claim 22, wherein the alkali solution has a pH of at least 12.
39. The cell as claimed in claim 22, wherein the alkali solution has a concentration of at least 1M.
40. The cell as claimed in claim 22, wherein the rGO is present in the form of layers, each layer having a thickness ranging from about 0.1 mm to 0.3 mm.
41. The cell as claimed in claim 22, wherein the rGO is present in the form of layers; and the electrical energy, measured as electrical current, increases as the layers of rGO increase.
42. The cell as claimed in claim 41, wherein the electrical current increases until the oxygen diffuses through the layers of rGO.
43. The cell as claimed in claim 22, wherein the cell shape is selected from a group consisting of rectangular shape, square shape, circular shape, oval shape, cylindrical shape, cube shape, cuboid shape, sheet type, collective sheet type forming a book of different sizes, and combinations thereof.
44. A system comprising a plurality of cells as claimed in any of the preceding claims, wherein the plurality of cells is connected in series or in parallel or a combination thereof.