DESC:FIELD OF THE INVENTION
The field of the invention relates to electrochemical cells designed for the production of organic and/or inorganic chemicals and gases. More specifically, the invention pertains to the configuration and operation of such cells utilizing gas diffusion electrodes, a porous separator for electrolyte transfer, and a novel electrolyte recirculation mechanism driven by the generated gases, eliminating the need for external pumping systems.

BACKGROUND OF THE INVENTION
As the world grapples with environmental challenges and the need for sustainable chemistry intensifies, electrochemical cells, with their various types and electrocatalytic systems, stand at the forefront of innovation. Electrochemical cells stand as pivotal tools in the world of chemistry and industry, enabling the conversion of chemical energy into electrical energy and vice versa through redox reactions. Their applications span across various fields, including power generation, energy storage, and the production of valuable chemicals.
A particularly noteworthy application of electrochemical cells is their role in facilitating the sustainable production of valuable chemicals. Electrochemical processes have gained prominence as environmentally friendly and efficient routes for chemical synthesis, enabling precise control and minimal waste. In this context, the versatility of electrochemical cells is (are) exemplified through their capacity to address specific challenges, such as the conversion of nitrogen and carbon dioxide, while advancing sustainable chemistry.
Electrochemical cells have redefined chemical production by offering innovative solutions to challenges that were once insurmountable through traditional means. Electrochemical cells encompass a wide array of designs, each tailored to specific applications. The primary categories include:
Galvanic Cells: These cells, also known as voltaic cells, are designed for spontaneous redox reactions to generate electrical energy. They are commonly found in batteries and serve as power sources for portable electronic devices.
Electrolytic Cells: In contrast to galvanic cells, electrolytic cells drive non-spontaneous reactions by applying an external voltage (energy). They play a crucial role in processes like electroplating and water electrolysis to produce hydrogen and oxygen gases.
Fuel Cells: Fuel cells generate electrical energy through the electrochemical reaction of fuel, typically hydrogen, and an oxidant, often oxygen from the air. They are highly efficient and offer a cleaner alternative to traditional combustion for power generation.
Flow Batteries: Flow batteries store electrical energy in chemical solutions and are particularly valuable for grid-level energy storage due to their scalability.
Current electrochemical cells face several limitations that hinder their widespread adoption and optimal performance. Electrochemical cells typically have a lower energy density compared to traditional fossil fuels, limiting their range and application in energy-intensive devices. Increasing the energy density of batteries and fuel cells is crucial for enhancing their practical viability. The overall efficiency of electrochemical cells, from chemical energy conversion to electrical energy output, is often suboptimal. Losses due to internal resistance, overpotential, and heat dissipation reduce the overall energy output. Improving the efficiency of these cells is essential for maximizing their energy utilization.
Attempts have been made to increase the efficiency of the electrochemical cells. For example, patent application WO2022056605A1 discloses a ‘zero-gap' cell structures for electro-synthesis. According to the disclosure, in the capillary-fed electrolysis (CFE) cell an aqueous electrolyte is constantly supplied to the electrodes by a spontaneous capillary action in the porous, hydrophilic, inter-electrode separator. The bottom end of the separator is dipped in a reservoir, resulting in capillary induced, upward, in-plane movement of electrolyte. The scale up of such a system would be limited, as the height of the electrolyte movement is restricted to a shorter distance due to the opposing gravitational force.
US patent No. US20170088959A1 describes an electrochemical cell which has a membrane located between two flow field plates. On a first side of the membrane, there is a porous support surrounded by a seal between the membrane and the flow field plate. On a second side of the membrane, there is a seal between the membrane and the flow field plate located inside of the gap. The electrochemical cell is useful, in high pressure or differential pressure electrolysis in which the second side of the membrane will be consistently exposed to a higher pressure than the first side of the membrane.
US 4,758,322 discloses an electrolytic cell, the so-called filter press configuration where several bipolar cells are stacked in series and are integrally arranged between two end plates connected to each other by tie rods. Each bipolar cell comprises an anode chamber and a cathode chamber separated by a diaphragm or membrane. Each cell is then separated from the next by conductive walls (so-called bipolar plates) having opposite polarities on the two faces. The stack of cells is secured together by end plates that form the anode (+) and cathode (-) terminal connections of the stack. The end plates are pressed together by tie rods that are electrically isolated to prevent cell shorting. A liquid electrolyte is introduced into the cell and the gas produced is collected from the cell. This electrolyzer has a limited ability to operate under internal pressure, i.e. in pressurized electrolyte and product gas.
US 6,153,083 describe an electrolytic cell for electrolysis of water under pressure, in which a bipolar cell stack is enclosed in a pressure vessel. Two end electrodes of the stack are connected to a power source by two lead-in cables extending through the pressure vessel, and the interior of the pressure vessel is filled with pressurized water surrounding the cell stack. However, although not described in detail, the disadvantages of this design, which are very difficult to solve in practice, are the cable passages through the pressurized vessel, as well as an apparatus for supplying alkaline electrolyte to the interior of the cell stack.
Catalysts also play a critical role in electrochemical reactions, but their stability and selectivity can be limiting factors. Catalysts may degrade over time, leading to decreased performance and potential environmental concerns. Additionally, catalysts may produce unwanted side products, reducing the overall yield of the desired product. Electrolytes are essential components of electrochemical cells, providing a medium for ion transport. However, electrolytes often face limitations in terms of their operating temperature range, conductivity, and stability. Developing electrolytes with improved properties is crucial for expanding the applicability of electrochemical cells.
Some electrochemical reactions, such as the Nitrogen (N2) reduction reaction (NRR), nitrate and nitrite reduction reaction and the CO2 reduction reaction (CO2RR), are thermodynamically uphill processes. Developing strategies to reduce energy consumption and improve overall efficiency is essential for making these reactions more practical. Also, developing scalable and cost-effective electro-catalytic systems for industrial applications is essential for widespread adoption. This involves addressing challenges in reactor design, and process optimization which remains the object of the present invention.

SUMMARY OF THE INVENTION:
In an aspect, the present invention provides electrochemical cells, more specifically of zero-gap architecture, which are inherently energy efficient and utilizes in situ pressure for flow of electrolyte in addition to capillary and/or diffusion and/or osmotic effects to maximize the cell performance.
In a preferred aspect, the present invention provides an electrochemical cell comprising:
a. a first gas diffusion electrode (16) and second gas diffusion electrode (17) which are inserted into separate first and second electrolyte or gas compartments (11,13);
b. a spacer or porous material or thin membrane (9) disposed between the first gas diffusion electrode (16) and second gas diffusion electrode (17);
c. an electrolyte chamber (21) within the cell configured to supply electrolyte to the spacer or porous material or thin membrane (9);
d. electrolyte reservoirs positioned relative to the electrochemical cell to enable electrolyte flow to the electrolyte chamber (21) and electrolyte or gas compartments (11,13).
wherein the flow of electrolyte in the spacer or porous material or thin membrane (9) is by capillary and/or diffusion and/or osmotic effects in addition to gravity flow,
wherein the electrolyte flow to the first and second electrolyte or gas compartments (11,13) is achieved by gravity without the use of pumps; and
wherein electrolyte recirculation in the electrolyte chamber (21) and the first and second electrolyte or gas compartments (11,13) to the respective electrolyte reservoir is facilitated by in-situ pressure generated by gaseous products within the electrochemical cell.
In another aspect, a catalyst may be incorporated in the first and second gas diffusion electrodes (16, 17) of the electrochemical cell to facilitate electrochemical reactions.
In another aspect, the first and second gas diffusion electrodes (16, 17) of the present invention are selected from the group consisting of, but not limited to, carbon papers, carbon cloths, graphite, nickel foam, nickel fibers, nickel mesh, copper foam, copper fibers, copper mesh, titanium foam, titanium fibers, titanium mesh, iron mesh, iron foam, iron fibers, various alloys containing iron and stainless-steel including its alloys in various porous forms or a combination thereof.
In another aspect, the electrochemical cell used to produce various chemicals comprises of the first and second gas diffusion electrodes (16, 17) which are tightly sandwiched against each other on opposite sides of a spacer or thin membrane or porous material (9), which may inherently have a high ionic conductance or may be filled with a liquid electrolyte having a high ionic conductance.
In yet another aspect, the electrochemical cell is supplied with the electrolyte from an electrolyte reservoir. According to certain aspects of the invention the electrolyte reservoir could be positioned above the electrochemical cell or positioned at the bottom of the cell or according to certain aspects of the invention be positioned at the side of the electrochemical cell.
In another aspect, the electrolyte chamber (21) in the electrochemical cell is positioned at the top or bottom, or both top and bottom or surrounding the electrodes (16, 17) and the first and second electrolyte or gas compartments (11, 13).
In another aspect, the electrolyte from the electrolyte reservoir is fed into the electrolyte chamber (21) in the electrochemical cell through one or multiple electrolyte channels (33 or 36).
In another aspect, a spacer or porous material or a thin membrane (9) is in physical contact with the electrolyte present in the electrolyte chamber (21) of the electrochemical cell. The bottom of the spacer or porous material or thin membrane (9) is in direct contact with the electrolyte in the electrolyte chamber (21) or preferably more than one side of the spacer or porous material or thin membrane (9) is in direct contact with the electrolyte in the electrolyte chamber (21) or more preferably on all the four sides of the spacer or porous material or thin membrane (9) is in direct contact with the electrolyte in the electrolyte chamber (21).
In another aspect, the electrolyte movement in the electrochemical cell is controlled by differential positive or negative pressure in the electrolyte chambers (21) in addition to capillary, diffusion, or osmotic effects. The differential positive or negative pressure in the electrolyte chambers (21) enhances the capillary, diffusion, or osmotic effect.
In yet another aspect, the differential pressure in the electrochemical cell is maintained by a combination of positive and negative pressures applied to different electrolyte chambers (21).
In another aspect, the flow of electrolyte from the electrolyte reservoir to the first and second electrolyte or gas compartments (11, 13) is achieved by gravity without the use of pumps.
In yet another aspect, the electrolyte recirculation in the electrolyte chamber (21) and the first and second electrolyte or gas compartments (11, 13) to the respective electrolyte reservoir is facilitated by in-situ pressure generated by gaseous products within the electrochemical cell.
In another aspect, the electrochemical cell is arranged as a plurality of said cells. The plurality of said electrochemical cell is stacked and configured to operate under an internal pressure more preferably under an in-situ pressure generated by gaseous products comprising a fluid connection for supplying electrolyte to the cell stack from separate electrolyte reservoirs, a fluid connection for collecting products of electrochemical reaction from the cell stack, and an anode and cathode with an electrical connection.
In another aspect, the present invention provides a method of synthesis of organic and inorganic chemicals in the electrochemical cell, comprising;
i. Introducing the electrolyte, the catholyte and the anolyte from the respective reservoirs into the designated compartments by gravity and/ or differential pressure;
ii. Supplying the electrical power to the cathode and the anode to initiate the electrochemical process for production of desired gases and/or products wherein the in-situ pressure generated by gaseous products facilitates the flow and recirculation of the electrolyte, the catholyte and anolyte; and
iii. separating the product and/ or gases from the catholyte, anolyte and electrolyte and recycling the catholyte, anolyte and electrolyte.
In another aspect, the present invention provides the use of the electrochemical cell for the synthesis of organic and inorganic chemicals using feed gas comprising of N2, NO, NO2, N2O, N2O5, NOx mixtures, CO2 and a combination thereof.
In another aspect, the present invention provides the use of the electrochemical cell for the synthesis of organic and inorganic chemicals like, but not limited to, ammonia, urea, nitric acid, hydrazine, ammonium salts (Ammonium nitrates, Ammonium sulphates, Ammonium carbonates), methane, ethane, propane, butane, hexane, carbon monoxide, formic acid, ethylene, propylene, acetylene, methanol, ethanol, propanol, hydrogen, oxygen, chlorine, hydrogen peroxide, or water.
In yet another aspect, the present invention provides the use of the electrochemical cell as fuel cell to generate energy (power) on supplying gases selected from but not limited to hydrogen, oxygen, methanol, ammonia, or combinations thereof.

DESCIRPTION OF DRAWINGS
Figure 1 – schematic diagram showing the details of the electrochemical cell as an example of an embodiment;
Figure 2 – schematic diagram showing the details of the electrochemical cell as an example of an embodiment;
Figure 3 – schematic diagram showing the details of the electrochemical cell as an example of an embodiment;
Figure 4 – schematic diagram showing the details of the electrochemical cell stack as an example of an embodiment;
Figure 5 – schematic diagram showing the details of the electrochemical cell stack as an example of an embodiment.

DETAILED DESCRIPTION OF THE INVENTION
The following invention describes in particular the preferred and optional embodiments so that the various aspects therein can be more clearly understood and appreciated.
The present invention broadly discloses electrochemical cells, more specifically of zero-gap architecture, which are inherently energy efficient and utilizes pressure assisted flow of electrolyte in addition to capillary and/or diffusion and/or osmotic effects to maximize the cell performance.
A zero-gap electrochemical cell is a type of electrochemical reactor where the anode and cathode are positioned with minimal or no physical separation, typically with only a thin membrane or separator or electrolyte layer in between. This design reduces ohmic losses and enhances mass transfer, leading to improved efficiency in electrochemical reactions.
According to certain embodiments of the invention, the electro-synthetic cell may be considered as an electrochemical cell that continuously produces one or more organic and/ or inorganic chemical substances, over an indefinite period of time, for use outside of the cell. A chemical substance can be in the form of a gas, liquid or solid. The reactants and products are continuously supplied or removed from the cell during operation. These cells also require an additional continuous input of electrical energy.
In a preferred embodiment, the present invention provides an electrochemical cell comprising:
a. a first gas diffusion electrode (16) and second gas diffusion electrode (17) which are inserted into separate first and second electrolyte or gas compartments (11,13);
b. a spacer or porous material or thin membrane (9) disposed between the first gas diffusion electrode (16) and second gas diffusion electrode (17);
c. an electrolyte chamber (21) within the cell configured to supply electrolyte to the spacer or porous material or thin membrane (9);
d. electrolyte reservoirs positioned relative to the electrochemical cell to enable electrolyte flow to the electrolyte chamber (21) and electrolyte or gas compartments (11,13);
wherein the flow of electrolyte in the spacer or porous material or thin membrane (9) is by capillary and/or diffusion and/or osmotic effects in addition to gravity flow,
wherein the electrolyte flow to the first and second electrolyte or gas compartments (11,13) is achieved by gravity without the use of pumps; and
wherein electrolyte recirculation in the electrolyte chamber (21) and the first and second electrolyte or gas compartments (11,13) to the respective electrolyte reservoir is facilitated by in-situ pressure generated by gaseous products within the electrochemical cell.
In another embodiment, a catalyst may be incorporated in the first and second gas diffusion electrodes (16, 17) of the electrochemical cell to facilitate electrochemical reactions.
According to certain embodiments of the invention, the electrochemical cell (As shown in figure 1 or 2 or 3) used for the production of various chemicals, comprises of two electrodes (16, 17) which are tightly sandwiched against each other on opposite sides of a spacer or porous material or thin membrane (9), which may inherently have a high ionic conductance or may be filled with a liquid electrolyte having a high ionic conductance.
According to certain embodiments of the invention, the spacer or porous material or thin membrane (9) has thickness preferably less than 1 mm, or preferably less than 0.5 mm, or preferably less than 0.35 mm, or preferably less than 0.2 mm, or preferably less than 0.1 mm or preferably less than 0.05 mm or preferably less than 0.025 mm. In addition, the spacer or porous material or thin membrane (9) has an average pore diameter preferably between 0.5 µm and 200 µm. Preferably, the spacer or porous material or thin membrane (9), has a porosity of at least 10%.
According to certain embodiments of the invention, the spacer, porous material, or thin membrane (9) is selected from materials that exhibit high ionic conductivity, preferably for anions, more preferably for cations, and even more preferably for protons. In certain other embodiments, it may be selected from materials that are insulating in nature.
In another embodiment, the electrochemical cell is supplied with the electrolyte/s from electrolyte reservoirs. According to certain embodiments of the invention the electrolyte reservoirs could be positioned above the electrochemical cell or positioned at the bottom of the cell or according to certain aspects of the invention be positioned at the side of the electrochemical cell.
In another embodiment, the electrolyte from the electrolyte reservoir/s is fed into the electrolyte chamber (21) in the electrochemical cell through one or multiple electrolyte channels (33, 36). The electrolyte channels (33, 36) aid in the continuous recirculation of the electrolyte to the electrolyte chamber (21) in the electrochemical cell from the electrolyte reservoir/s.
In yet another embodiment, the electrolyte chamber (21) could be at the bottom of the electrodes (16, 17) and the first and second electrolyte or gas compartments (11,13) in the electrochemical cell or at the top of the electrodes (16, 17) and the first and second electrolyte or gas compartments (11,13) in the electrochemical cell.
In another embodiment of the present invention, the electrolyte chamber (21) is present both at the top and bottom of the electrodes (16, 17) and the first and second electrolyte or gas compartments (11,13) in the electrochemical cell or more preferably the electrolyte chamber (21) surrounds the entire electrodes (16, 17) and the first and second electrolyte or gas compartments (11,13).
In a further embodiment of the present invention, a spacer or porous material or a thin membrane (9) is in direct physical contact with the electrolyte present in the electrolyte chamber (21) of the electrochemical cell. The bottom of the spacer or porous material or thin membrane (9) is in direct contact with the electrolyte in the electrolyte chamber (21) or preferably more than one side of the spacer or porous material or thin membrane (9) is in direct contact with the electrolyte in the electrolyte chamber (21) or more preferably all the sides of the spacer or porous material or thin membrane (9) is in direct contact with the electrolyte in the electrolyte chamber (21).
In yet another embodiment, the spacer or porous material or thin membrane (9) may transfer the electrolyte from the electrolyte chamber (21) by capillary and/or diffusion and/or osmotic effects.
In another embodiment, the movement of the electrolyte in the spacer or porous material or thin membrane (9) is controlled by maintaining a differential pressure across the electrolyte chambers (21) in addition to capillary and/or diffusion and/or osmotic effects thereby enhancing these effects. The differential pressure is maintained by differential positive or negative pressure. The differential pressure is maintained by a combination of positive and negative pressures applied to different electrolyte chambers (21).
In some embodiments, the differential pressure is maintained by a positive pressure in the lower electrolyte chamber (21) and a positive pressure, which is slightly lower than the pressure in the bottom electrolyte chamber (21), in the top electrolyte chamber (21) and vice versa.
In another embodiment, the differential pressure is maintained by a positive pressure in the lower electrolyte chamber (21) and a negative pressure in the top electrolyte chamber (21) and vice versa.
In yet another embodiment of the present invention, the differential pressure is maintained by a positive or negative pressure in the lower electrolyte chamber (21) or top electrolyte chamber (21) and vice versa.
In another embodiment, the differential pressure is maintained by a negative pressure in the lower electrolyte chamber and a negative pressure, which is slightly lower than the pressure in the bottom electrolyte chamber (21), in the top electrolyte chamber and vice versa.
In yet another embodiment, the differential pressure includes the gravitational forces more preferably the differential pressure is higher than gravitational forces to enable controlled for of the electrolyte.
In some embodiments, the integrity of the spacer or porous material or thin membrane (9) is retained by precise control of the trans membrane pressure.
In another embodiment, the electrolytes are selected from a wide range of materials, including but not limited to, aqueous electrolytes, non-aqueous electrolytes, polymer electrolytes, ionic liquids, and solid-state electrolytes. The electrolyte/s may facilitate the transport of anions, cations, or protons, depending on the specific application. Suitable examples include acidic, alkaline, and neutral electrolytes, such as but not limited to sulfuric acid, phosphoric acid, potassium hydroxide, sodium hydroxide, sodium salts, potassium salts, carbonate and bicarbonate salts, lithium salts, ammonium salts, perfluorinated sulfonic acid polymers (e.g., Nafion), acidic buffers, basic buffers, neutral buffers, other ion-conducting materials etc and the like.
In a further embodiment, the spacer or porous material or thin membrane (9) is preferably inserted between the first-gas diffusion electrode (16) and the second-gas diffusion electrode (17). Preferably, the first gas diffusion electrode (16) is located in the middle of the electrolyte chamber/s (21). Preferably, the second electrode (17) is also located in the middle of the electrolyte chamber/s (21).
In some embodiments of the invention, first-gas diffusion electrode (16) and the second-gas diffusion electrode (17) are located outside the electrolyte chamber (21).
In another embodiment, the first and second gas diffusion electrodes (16, 17) are smaller than the capillary spacer or porous material or thin membrane (9).
In yet another embodiment, the first gas diffusion electrode (16) and second gas diffusion electrode (17) are selected from, but not limited to, carbon-based materials (such as carbon papers, carbon cloths, and graphite), nickel-based materials (such as nickel foam, nickel fibers, and nickel mesh), copper-based materials (such as copper foam, copper fibers, and copper mesh), titanium-based materials (such as titanium foam, titanium fibers, and titanium mesh), and various stainless steel alloys in the form of foams, fibers, or meshes. The electrodes may also comprise combinations of these materials, composite structures, or other electrically conductive and/ or catalytically active materials suitable for electrochemical applications. In another embodiment, the first gas diffusion electrode (16) and second gas diffusion electrode (17) have an architecture made with interlaced strands of metal, fibre or other flexible or ductile materials. The interlaced strands could be porous to provide higher surface area. In certain embodiments the interlaced strands could be having parallel rows of folds that look like a series of waves when seen from the edge.
In another embodiment, the first-gas diffusion electrode (16) and the second-gas diffusion electrode (17) may contain a catalyst which aid in the production of various chemicals from gases or liquids. The catalyst is introduced to the first-gas diffusion electrode (16) and the second-gas diffusion electrode (17) by any methods known in the art. Preferably, the catalyst-coated side of the first-gas diffusion electrode (16) and the second-gas diffusion electrode (17) are in contact with the capillary spacer or porous material or thin membrane (9). The membrane electrode assembly (MEA) is the common designation for this three-combination structure.
In another embodiment, the membrane electrode assembly (MEA) in the electrochemical cell comprises the combination of the first gas diffusion electrode (16), second gas diffusion electrode (17), and the spacer or porous material or thin membrane (9) between the two electrodes.
In another embodiment, the membrane electrode assembly in the electrochemical cell in addition to first gas diffusion electrode (16), second gas diffusion electrode (17), and the spacer or porous material or thin membrane (9) between the two electrodes comprises of cation and/or anion exchange membranes positioned on either side of the spacer or porous material or thin membrane (9).
In yet another embodiment, the catalyst in the first gas diffusion electrode (16) is selected from the group consisting of metal nanoparticles, metal alloys, metal oxides, and carbon-based materials with electrochemical activity.
In yet another embodiment, the first gas diffusion electrode (16) may contain a catalyst selected from, but not limited to, metal nanoparticles (e.g., Co, Cu, Ni, Zn, Cd, Ag, Au, Pt, Pd, Ir, Ru, Fe, Ti), metal-carbon composites (e.g., Pt-C), doped carbon materials (e.g., Bi-doped graphene, black phosphorus), metal alloys (e.g., Cu-Bi, Au-Cu, RhCu-uls, CoMoP@C, NiCoP/NF), transition metal oxides and hydroxides (e.g., Co3O4, CoNi hydroxide, NiO/Ni, CuWO4, Ni?-N-C, Ru-Co3O4??), metal-organic frameworks (e.g., MOP, In(OH)3-S), single-atom catalysts (e.g., Fe-N4, Sc/NC, Fe-SAC, Ni-SAC, Co-SAC, Ru SAs/N-C), phosphides and carbides (e.g., Mo2C, Mo5N6, NiCoP/NF, C-Co2P), hybrid materials (e.g., TiO2-Nafion-ITO, PdCu-TiO2, Cu-CeO2, BiFeO3/BiVO4), functionalized nanostructures (e.g., Te-Pd NCs, Zn NB, Y/NC, B-FeNi-DASC), conductive polymers (e.g., PPy-Pt, PSS-PPy/Ni-Co-P), metal-doped carbon nanostructures (e.g., Fe@C-Fe3O4/CNTs, Bi2S3/N-RGO, Co-NiO?@GDY, Cu-N-C), and ionic-functionalized materials (e.g., 1-ethyl-3-methylimidazolium-functionalized Mo3P). The catalyst may also be a combination of these materials, tailored to enhance electrochemical performance.
In yet another embodiment, the catalyst in the second gas diffusion electrode (17) is selected from transition metal oxides, phosphides, nitrides, hydroxides, and their combinations.
In another embodiment, the second gas diffusion electrode (17) may contain a catalyst selected from, but not limited to, transition metal oxides (e.g., NiFe2O4, CoO?, NiCoO?, NiO?, IrO2, RuO2), hydroxides (e.g., Ni(OH)2, Fe-Ni(OH)2), perovskite materials (e.g., La0.5Sr0.5CoO3), phosphides (e.g., Ni2P-Fe2P, CoP?@FeOOH), nitrides (e.g., Ni3N/Ni, NiMoN, NiFeMoN), sulfides (e.g., Ni3S2), borides (e.g., Ti@NiB, NiFeB?), and their combinations thereof. The catalyst composition may be tailored to optimize electrochemical performance based on specific application requirements.
In certain embodiments of the present invention, the catalyst is incorporated into the first and second gas diffusion electrodes (16, 17) by using ionomers like, but not limited, Nafion, Sustaion, Polystyrene methyl methylimidazolium chloride (PSMIM), Polystyrene tetramethyl methylimidazolium chloride (PSTMIM) and their combinations thereof.
In yet another embodiment, the spacers or porous materials or thin membranes (9) are selected from, but not limited to, Paratetrafluoroethylene (PTFE), fluorinated polymers such as Nafion (115, 117, 212), Porous-thin ceramic sheets, PP-PE-PP separator, Zirfon, solid oxide, anion membranes such as Aemion, Pention, Fumacep, Piperion, Sustainion and their combinations thereof.
According to certain embodiments of the invention, the first gas diffusion electrode (16) is in direct contact with the first electrolyte or gas compartment (11) and the second gas diffusion electrode (17) is in direct contact with the second electrolyte or gas compartment (13). The first gas diffusion electrode (16) and second gas diffusion electrode (17) are each independently inserted into the first electrolyte or gas compartment (11) and the second electrolyte or gas compartment (13) respectively of two halves of the cell. Preferably, the first and second electrolyte or gas compartments (11,13) are isolated from the electrolyte chamber (9).
In some embodiments of the present invention, first electrolyte or gas compartment (11) which is in direct contact with the first gas diffusion electrode (16), preferably comprises of at least two ports (44, 43). At least one of the ports provided to the first electrolyte or gas compartment (11) is used for providing the gaseous reactant or a reactant dissolved in a liquid electrolyte to the electrochemical cell and at least one of the ports, preferably in a position opposite to the reactant entry is utilized for removal of the product gas or a product dissolved in a liquid electrolyte from the chemical cell. The first electrolyte or gas compartment (11) which is in direct contact with the first gas diffusion electrode (16) preferably may also comprises of several channels that increase the residence time of the gas or liquid electrolyte in the chamber. The channels could be of serpentine nature or other geometry that increase the residence time of the gas or liquid electrolyte in the electrolyte or gas compartment (11).
In yet another embodiment of the invention, the second electrolyte or gas compartment (13) which is in direct contact with the second gas diffusion electrode (17), preferably comprises of at least two ports (15, 18). At least one of the ports provided to the second electrolyte or gas compartment (13) is used for providing the gaseous reactant or inert gas or a reactant dissolved in a liquid electrolyte to the electrochemical cell and at least one of the ports, preferably in a position opposite to the reactant or inert gas entry is utilized for removal of the product gas or inert gas or a product dissolved in a liquid electrolyte from the chemical cell. The second electrolyte or gas compartment (13) which is in direct contact with the second gas diffusion electrode (17), preferably comprises of several channels that increase the residence time of the gas in the chamber. The channels could be of serpentine nature or other geometry that increase the residence time of the gas or liquid electrolyte in the electrolyte or gas compartment (13).
In yet another embodiment of the invention, the electrolyte flow in the first electrolyte or gas compartment (11) and/ or second electrolyte or gas compartment (13) and/ or electrolyte chamber (9) is carried out by gravity without the use of pumps. The individual electrolyte reservoirs, in this are placed above the electrochemical cell and the recirculation of the electrolytes in the respective chambers is achieved by in-situ pressure generated by gaseous products within the electrochemical cell.
According to some embodiments, the diameter of the tubes or conduits, for the flow of electrolytes from the individual electrolyte reservoirs to the first electrolyte or gas compartment (11) and/ or second electrolyte or gas compartment (13) and/ or electrolyte chamber (9), could be increased or decreased to advantageously enable variable flow of electrolytes to the respective compartments.
According to some embodiments of the invention, the electrochemical cell comprises of monopolar or bipolar plates (14) adjacent to the first electrode gas diffusion electrode (16) and second gas diffusion electrode of the cell which serves as current collectors and give power to the first gas diffusion electrode (16) and second gas diffusion electrode (17), respectively. The bipolar or monopolar plates (14) in the cell can be utilized for connecting leads of positive terminal and negative terminal of a power source or battery or potentiostat for providing power supply.
In another embodiment of the present invention, a plurality of electrochemical cell is stacked (as shown in figure 4 or 5), and configured to operate under an internal pressure more preferably under an in-situ pressure generated by gaseous products. The system comprising of an electrochemical cell stack, and a fluid connection for supplying electrolyte to the cell stack, a fluid connection for collecting products of electrochemical reaction from the cell stack, and at least an anode and cathode with an electrical connection.
In another embodiment, the present invention provides a method of synthesis of organic and inorganic chemicals in the electrochemical cell, comprising;
i. Introducing the electrolyte, the catholyte and the anolyte from the respective reservoirs into the designated compartments by gravity and/or differential pressure;
ii. Supplying the electrical power to the cathode and the anode to initiate the electrochemical process for production of desired gases and/ or products wherein the in-situ pressure generated by gaseous products facilitating the flow and recirculation of the electrolyte, the catholyte and anolyte; and
iii. separating the product and/ or gases from the catholyte, anolyte and electrolyte and recycling the catholyte, anolyte and electrolyte.
In another embodiment, the electrochemical cell of the present invention is more efficient in synthesis of organic and inorganic chemicals as compared to conventional electrochemical cells.
In another aspect, the present invention provides the use of the electrochemical cell for the synthesis of organic and inorganic chemicals using feed gas comprising of N2, NO, NO2, N2O, N2O5, NOx mixtures, CO2 and a combination thereof.
In certain embodiments, the feed gases supplied to the electrochemical cell may comprise nitrogen oxides, including but not limited to nitric oxide (NO), nitrogen dioxide (NO2), and other NO? species. These gases may be produced through plasma-based processes or other methods such as thermal, catalytic, or electrochemical oxidation of nitrogen-containing compounds. The composition of the feed gases may vary depending on the production method and operating conditions
In another embodiment, the present invention provides the use of the electrochemical cell for the synthesis of organic and inorganic chemicals like, but not limited to, ammonia, urea, nitric acid, hydrazine, ammonium salts (Ammonium nitrates, Ammonium sulphates, Ammonium carbonates), methane, ethane, propane, butane, hexane, carbon monoxide, formic acid, ethylene, propylene, acetylene, methanol, ethanol, propanol, hydrogen, oxygen, chlorine, hydrogen peroxide, or water.
In yet another embodiment, the present invention provides the use of the electrochemical cell as fuel cell to generate energy (power) on supplying gases selected from hydrogen, oxygen, methanol, ammonia, or combinations thereof.

ADVANTAGES
Following are advantages of the process.
• The cell is versatile and can be used for the production of various chemicals as well as energy generation.
• The process can be run at ambient temperature conditions.
• This process does not require noble/ precious catalysts such as Pt, Au, Ag, Ir
• The design is simple and easy for scale up with complete process automation.
• The performance of the cell is enhanced because the flow of electrolyte in porous capillary spacer or separator or membrane employed and electrolyte or gas compartments is controlled and regulated by in situ pressure.
• The zero-gap design of the electrochemical cell helps in reduction of the overall energy required for the production of different chemicals.

The following examples which include the preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

EXAMPLES:
Example 1: Comparison of gas production with conventional electrochemical cells
Different electrochemical cells, conventional flow cell, electrochemical cell with electrolyte chamber in the bottom, electrochemical cell with electrolyte chamber in the top and bottom and electrochemical cell with electrolyte chamber on all sides were assembled. Different electrolytes from reservoirs were introduced into their designated chambers by gravity. Once the chambers were filled, electrical power is supplied to the cathode and anode terminals using a potentiostat.
The gases produced in the electrochemical cells were then collected in an inverted water column and rate of gas production was estimated.
Table 1
Electrolyte used Electrochemical cell type and gas production in ml/h
Conventional flow cell Bottom electrolyte chamber Top and bottom electrolyte chamber All side electrolyte chamber
1 M KOH 380 560 1130 1500
200 mM KNO3 + 1 M KOH 260 540 840 1320
1 M KNO3 + 1M KOH 93 560 610 1500

Example 2: Comparison of flow rate achieved with conventional electrochemical cells
Different electrochemical cells, conventional flow cell, electrochemical cell with electrolyte chamber in the top and bottom and electrochemical cell with electrolyte chamber on all sides were assembled. Different electrolytes from reservoirs were introduced into their designated chambers by gravity. Once the chambers were filled, electrical power is supplied to the cathode and anode terminals using a potentiostat. The recirculation flow rate achieved in the different electrochemical cells were measured.
Table 2
Electrolyte used Electrochemical cell type and gas production in ml/min
Conventional flow cell Top and bottom electrolyte chamber All side electrolyte chamber
1 M KOH 35 270 380
200 mM KNO3 + 1 M KOH 12 140 240

Example 3: Electrochemical Process of Nitrate Reduction into Ammonia:
The electrolytic cell or stack is assembled carefully as illustrated in Figure 1. The catholyte and anolyte from their respective reservoirs were introduced into their designated chambers by gravity. Once the chambers were completely filled, electrical power is supplied to the cathode and anode terminals using a DC power source or potentiostat.
Upon reaching the desired power input, the electrochemical process initiates, leading to the production of gaseous products. The in-situ pressure generated during the reaction facilitates the flow and recirculation of both the catholyte and anolyte.
After 1 hour, the catholyte is sampled and analyzed for ammonia formation using ion chromatography.
A summary of the experimental variations, including different cell/stack configurations, separators, reactant concentrations, and other parameters, is presented in the table below.
Table 3
Example
No. Cell Type Reactant Electrolyte Membrane /Separator/
Spacer Anode Material Cathode Material Current Density (A cm-2) Ammonia Production Rate (ppm cm-2h-1)
1 All Sides Cavity (Single Cell) 200 mM KNO3 1 M KOH Nafion-117 Stainless Steel Mesh Stainless Steel Mesh 0.61 977.60
2 All Sides Cavity (Single Cell) 200 mM KNO3 1 M KOH Zirfon Stainless Steel Mesh Stainless Steel Mesh 0.51 235.44
3 All Sides Cavity
(Single Cell) 200 mM KNO3 1 M KOH Poly Ether Sulfone (PES) Stainless Steel Mesh Stainless Steel Mesh 0.41 628.51
4 All Sides Cavity (Single Cell) 200 mM KNO3 1 M KOH Poly Phenyl Sulphide (PPS) Stainless Steel Mesh Stainless Steel Mesh 1.63 385.54
5 Two Sides Cavity
(Single Cell) 200 mM KNO3 1 M KOH Nafion-117 Stainless Steel Mesh Stainless Steel Mesh 1.11 38.56
6 Two Sides Cavity
(Single Cell) 200 mM KNO3 1 M KOH Zirfon
Stainless Steel Mesh Stainless Steel Mesh 0.67 110.11
7 Two Sides Cavity
(Single Cell) 200 mM KNO3 1 M KOH Poly Ether Sulfone (PES) Stainless Steel Mesh Stainless Steel Mesh 0.33 561.44
8 Two Sides Cavity
(Single Cell) 200 mM KNO3 1 M KOH Poly Phenyl Sulphide (PPS) Stainless Steel Mesh Stainless Steel Mesh 0.19 188.80
9 All Sides Cavity
(8- Cell Stack) 200 mM KNO3 1 M KOH Poly Phenyl Sulphide (PPS) Stainless Steel Mesh Stainless Steel Mesh 0.33 187.82
10 All Sides Cavity
(8- Cell Stack) 1 M KNO3 1 M KOH Poly Phenyl Sulphide (PPS) Stainless Steel Mesh Stainless Steel Mesh 0.22 391.67
12 All Sides Cavity
(8- Cell Stack) 2 M KNO3 1 M KOH Poly Phenyl Sulphide (PPS) Stainless Steel Mesh Stainless Steel Mesh 0.33 579.58
13 All Sides Cavity
(8- Cell Stack) 200 mM KNO3 1 M KOH Zirfon Stainless Steel Mesh Stainless Steel Mesh 0.22 166.67
14 All Sides Cavity
(8- Cell Stack) 200 mM KNO3 1 M KOH Nafion-117 Stainless Steel Mesh Stainless Steel Mesh 0.22 116.00
15 All Sides Cavity
(8- Cell Stack) 1 M KNO3 1 M KOH Nafion-117 Stainless Steel Mesh Stainless Steel Mesh 0.33 416.67
16 All Sides Cavity
(8- Cell Stack) 1 M KNO3 1 M KOH Nafion-117 NiFe on Ni Foam Co& Graphite NPs on Ni Foam 0.24 276.52

Example 4: Comparison of present Electrochemical Cell with conventional cell:
The electrochemical conversion of nitrate production was carried out in a conventional cell and compared with electrochemical cell as illustrated in figure 1. In both cases only a single cell was used. The reactant and electrolyte used in both the cells were 1 M KNO3 and 1 M KOH respectively. Stainless steel mesh was used as the cathode and anode material in both the systems. Nafion 117 was used as the separator or spacer in both the systems. The circulation of the electrolyte and reactant in the conventional cell was done using a peristaltic pump, whereas in the novel cell the flow was carried out with the help of gravity and recirculation was facilitated by in-situ pressure.
Table 4
Cell type Current Density (A cm-2) Ammonia Production Rate (ppm cm-2h-1)
Conventional flow cell (single cell) 0.22 94.44
All Sides Cavity (Single Cell) 0.20 228.67

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
,CLAIMS:
1. An electrochemical cell comprising:
a. a first gas diffusion electrode and second gas diffusion electrode which are inserted into separate first and second electrolyte or gas compartments;
b. a spacer or porous material or thin membrane disposed between the first gas diffusion electrode and second gas diffusion electrode;
c. an electrolyte chamber within the cell configured to supply electrolyte to the spacer or porous material or thin membrane;
d. electrolyte reservoirs positioned relative to the electrochemical cell to enable electrolyte flow to the electrolyte chamber and electrolyte or gas compartments;
wherein the flow of electrolyte in the spacer or porous material or thin membrane is by capillary and/or diffusion and/or osmotic effects in addition to gravity flow,
wherein the electrolyte flow to the first and second electrolyte or gas compartments is achieved by gravity without the use of pumps; and
wherein electrolyte recirculation in the electrolyte chamber and the first and second electrolyte or gas compartments to the respective electrolyte reservoir is facilitated by in-situ pressure generated by gaseous products within the electrochemical cell.
2. The electrochemical cell as claimed in claim 1, wherein a catalyst may be incorporated in the first and second gas diffusion electrodes to facilitate electrochemical reactions.
3. The electrochemical cell as claimed in claim 1, wherein the first and second gas diffusion electrodes are selected from, but not limited to, carbon-based materials (such as carbon papers, carbon cloths, and graphite), nickel-based materials (such as nickel foam, nickel fibers, and nickel mesh), copper-based materials (such as copper foam, copper fibers, and copper mesh), titanium-based materials (such as titanium foam, titanium fibers, and titanium mesh), and various stainless steel alloys in the form of foams, fibers, or meshes. The electrodes may also comprise combinations of these materials, composite structures, or other electrically conductive and/ or catalytically active materials suitable for electrochemical applications.
4. The electrochemical cell as claimed in claim 3, wherein the first gas diffusion electrode and second gas diffusion electrode have an architecture made with interlaced strands of metal, fibre or other flexible or ductile materials, wherein the interlaced strands could be porous material to provide higher surface area.
5. The electrochemical cell as claimed in claim 1, wherein the electrolyte reservoir is positioned above, below, or at the side of the electrochemical cell.
6. The electrochemical cell as claimed in claim 1, wherein the electrolyte chamber is positioned at the top or bottom or both top and bottom or surrounding the gas diffusion electrodes and the first and second electrolyte or gas compartments.
7. The electrochemical cell as claimed in claim 1, wherein the porous spacer or separator or membrane is in direct contact with the electrolyte in the electrolyte chamber on one or more sides.
8. The electrochemical cell as claimed in claim 1, wherein the electrolyte flow in the porous spacer or separator or membrane is through capillary and/ or gravity and/or diffusion and/or osmotic effects including the gravitational forces.
9. The electrochemical cell as claimed in claim 1,wherein it is configured to operate under an internal pressure more preferably under an in-situ pressure generated by gaseous products.
10. The electrochemical cell as claimed in claim 1, wherein electrolyte chamber and the first and second electrolyte or gas compartments are fluidically connected to respective electrolyte reservoirs and the electrolyte recirculation in the electrolyte chamber and the first and second electrolyte or gas compartments to the respective electrolyte reservoir is facilitated by in-situ pressure generated by gaseous products within the electrochemical cell.
11. The electrochemical cell as claimed in claim 2, wherein the catalyst in the first gas diffusion electrode is selected from the group consisting of metal nanoparticles, metal-carbon composites, doped carbon materials, metal alloys, transition metal oxides and hydroxides, metal-organic frameworks, single-atom catalysts, phosphides and carbides, hybrid materials, functionalized nanostructures, conductive polymers, metal-doped carbon nanostructures, and ionic-functionalized materials with electrochemical activity, the catalyst may also be a combination of these materials.
12. The electrochemical cell as claimed in claim 2, wherein the catalyst in the second gas diffusion electrode is selected from but not limited to, transition metal oxides, hydroxides, perovskite materials, phosphides, nitrides, sulphides, borides, and their combinations thereof.
13. The electrochemical cell as claimed in claim 1, wherein the electrolyte is selected from solutions containing but not limited to, aqueous electrolytes, non-aqueous electrolytes, polymer electrolytes, ionic liquids, and solid-state electrolytes.
14. The electrochemical cell as claimed in claim 13, wherein the electrolytes comprises acidic, alkaline, and neutral electrolytes, including, but not limited to sulfuric acid, phosphoric acid, potassium hydroxide, sodium hydroxide, sodium salts, potassium salts, carbonate and bicarbonate salts, lithium salts, ammonium salts, perfluorinated sulfonic acid polymers (e.g., Nafion), acidic buffers, basic buffers, neutral buffers, other ion-conducting materials.
15. The electrochemical cell as claimed in claim 1, wherein the porous spacer or separator or membrane are selected from, but not limited to, Para tetrafluoroethylene (PTFE), fluorinated polymers such as Nafion (115, 117, 212), Porous-thin ceramic sheets, PP-PE-PP separator, Zirfon, solid oxide, anion membranes such as Aemion, Pention, Fumacep, Piperion, Sustainion.
16. The electrochemical cell as claimed in claim 1, wherein the porous spacer or separator or membrane has a thickness greater than 0.025 mm, a porosity greater than 10% and an average pore diameter in the range of 0.5 µm to 200 µm.
17. The electrochemical cell as claimed in claim 1, wherein the first and second gas diffusion electrodes are inserted into separate first and second electrolyte or gas compartments, and are physically isolated from the electrolyte chamber.
18. The electrochemical cell as claimed in claim 1, wherein the first electrolyte or gas compartment and second electrolyte or gas compartment comprises electrolyte channels configured to increase residence time of the gas or liquid electrolyte.
19. The electrochemical cell as claimed in claim 1, wherein the membrane electrode assembly (MEA) in said electrochemical cell comprises the combination of the first gas diffusion electrode, second gas diffusion electrode, and the porous spacer or separator or membrane.
20. The electrochemical cell as claimed in claim 1, wherein said electrochemical cell is arranged as a plurality of said cells to form an electrochemical cell stack.
21. The electrochemical cell as claimed in claim 20, wherein electrochemical cell stack is configured to operate under an internal pressure more preferably under an in-situ pressure generated by gaseous products comprising a fluid connection for supplying electrolyte to the stack, a fluid connection for collecting products of electrochemical reaction from the stack, and an anode and cathode with an electrical connection.
22. A method of synthesis of organic and inorganic chemicals in the electrochemical cell as claimed in claim 1, comprising;
i. Introducing the electrolyte, the catholyte and the anolyte from the respective reservoirs into the designated compartments by gravity and/or differential pressure;
ii. Supplying the electrical power to the cathode and the anode to initiate the electrochemical process for production of desired gases and/ or products wherein the in-situ pressure generated by gaseous products facilitates the flow and recirculation of the electrolyte, the catholyte and anolyte; and
iii. Operating the electrochemical cell for a specific duration to produce the desired gases or product in the catholyte or anolyte; and
iv. Separating the product and/ or gases from the catholyte, anolyte and electrolyte and recycling the catholyte, anolyte and electrolyte.

23. Use of the electrochemical cell as claimed in any one of the preceding claims 1 to 22 for the synthesis of organic and inorganic chemicals like, but not limited to, ammonia, urea, nitric acid, hydrazine, ammonium salts (Ammonium nitrates, Ammonium sulphates, Ammonium carbonates), methane, ethane, propane, butane, hexane, carbon monoxide, formic acid, ethylene, propylene, acetylene, methanol, ethanol, propanol, hydrogen, oxygen, chlorine, hydrogen peroxide or water.
24. Use of the electrochemical cell as claimed in any one of the preceding claims 1 to 22 as fuel cell to generate energy (power) on supplying gases selected from hydrogen, oxygen, methanol, ammonia or combinations thereof.