Description:FIELD OF THE INVENTION
[0001] The invention relates to the field of renewable energy generation and sustainable power systems, and more particularly to a hydrovoltaic electricity generation system that employs functionalized metal oxide nanoparticles within tubular structures to harness water evaporation-induced charge separation, enabling continuous power generation through enhanced capillary action and electric double layer formation at the water-nanoparticle interface.

DESCRIPTION OF THE RELATED ART
[0002] The following description of the related art is intended to provide background information pertaining to the field of disclosure. This section may include certain aspects of the art that may be related to various features of the present disclosure. However, it should be appreciated that this section is used only to enhance the understanding of the reader with respect to the present disclosure, and not as admissions of the prior art.
[0003] Water evaporation is one of the most ubiquitous natural processes on Earth, with approximately 71% of the planet's surface covered by water. This continuous cycle of evaporation represents an enormous, yet largely untapped, source of renewable energy. Recent advances in nanotechnology have opened new possibilities for harvesting electrical energy from water evaporation through hydrovoltaic phenomena, where the interaction between water molecules and engineered nanomaterials generates usable electricity.
[0004] Conventional hydrovoltaic devices have primarily relied on carbon-based materials to generate electricity via water evaporation. However, these carbon-based systems suffer from relatively low voltage outputs, typically below 0.5V, which limits their practical applications. The inferior power output is primarily attributed to slower evaporation rates and insufficient charge collection at the electrode surfaces, representing fundamental barriers to commercialization.
[0005] To address these limitations, researchers have explored metal oxide nanomaterials such as ZnO, TiO₂, and Al₂O₃ for hydrovoltaic applications. Among these, aluminum oxide (Al₂O₃) has shown particular promise due to its natural hydrophilicity and stable chemical properties. Recent studies have reported Al₂O₃-based lateral thin-film devices achieving open-circuit voltages ranging from 0.33V to 3.18V. However, these devices predominantly utilize planar or thin-film configurations that inherently limit water-material interaction and require external energy sources such as light, heat, or wind for optimal operation.
[0006] The mechanism underlying hydrovoltaic electricity generation involves the formation of an electric double layer (EDL) at the solid-liquid interface. When water moves through porous nanomaterials via capillary action, charge separation occurs between the material surface and water molecules, creating a streaming potential. The efficiency of this process depends critically on the surface properties of the nanomaterial, including surface area, hydrophilicity, and surface charge characteristics.
[0007] Despite recent progress, existing hydrovoltaic devices face several challenges: (1) limited current output due to poor charge collection efficiency, (2) complex and costly fabrication processes, (3) inability to maintain stable long-term operation, and (4) insufficient power density for practical applications. Furthermore, most reported devices focus solely on power generation without considering potential multifunctional applications that could enhance their commercial viability.
[0008] Therefore, there exists a requirement for an improved hydrovoltaic system that can generate higher current outputs while maintaining substantial voltage levels, utilize simple and scalable fabrication methods, and provide stable long-term operation for practical energy harvesting applications.

OBJECTS OF THE PRESENT DISCLOSURE
[0009] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0010] An object of the present disclosure is to provide a hydrovoltaic electricity generation system including functionalized metal oxide nanoparticles with nitrogen-containing functional groups and negative zeta potential for water evaporation-induced charge separation.
[0011] An object of the present disclosure is to provide a system generating electricity through capillary action-driven water transport through functionalized metal oxide nanoparticles having a surface area of 80-100 m²/g within tubular structures.
[0012] An object of the present disclosure is to provide a method for functionalizing metal oxide nanoparticles through hydrothermal treatment with hydrazine hydrate at 90-110°C for 10-14 hours to create hydrophilic N-H bonding sites.
[0013] An object of the present disclosure is to provide a hydrovoltaic device configuration with first and second electrodes separated by functionalized metal oxide nanoparticles establishing an electrical pathway for charge collection during water evaporation.
[0014] An object of the present disclosure is to provide an electrical interconnection network for connecting multiple hydrovoltaic devices in series or parallel configurations through distribution channels from a main water reservoir.
[0015] An object of the present disclosure is to provide a system for electrochemical degradation of organic dyes utilizing electricity generated from the hydrovoltaic device with graphite and platinum electrodes.
[0016] An object of the present disclosure is to provide a three-dimensional tubular structure with perforated electrodes and water-permeable material for maintaining continuous water flow through functionalized metal oxide nanoparticles.

SUMMARY
[0017] This section is provided to introduce certain objects and aspects of the present disclosure in a simplified form that are further described below in the detailed description. This summary is not intended to identify the key features or the scope of the claimed subject matter.
[0018] The present disclosure generally relates to renewable energy generation and sustainable power systems. More particularly, the present disclosure relates to a hydrovoltaic electricity generation system including functionalized metal oxide nanoparticles within tubular structures that enables continuous power generation through water evaporation-induced charge separation, providing enhanced electrical output through nitrogen-containing functional groups and negative zeta potential for improved charge collection and transport at the water-nanoparticle interface.
[0019] An aspect of the present disclosure relates to a system for generating electricity from water evaporation. The system includes a water distribution system including a main water reservoir and distribution channels extending therefrom for supplying water to multiple hydrovoltaic devices. The system includes a plurality of hydrovoltaic power generation devices fluidly connected to the distribution channels, wherein each device includes a tubular structure defining an internal cavity extending from a second end to a first end. The system includes a second electrode positioned at the second end of the tubular structure having at least one perforation therethrough for water passage. The system includes a water-permeable material disposed on the second electrode covering the perforation and being in fluid communication with the distribution channels for receiving water therefrom. The system includes functionalized metal oxide nanoparticles filling the internal cavity and supported by the water-permeable material, wherein the nanoparticles include metal oxide having nitrogen-containing functional groups with N-H bonds providing hydrophilic sites and exhibiting a negative zeta potential in aqueous solution. The system includes a first electrode positioned at the first end of the tubular structure in electrical contact with the functionalized metal oxide nanoparticles, wherein the electrodes are separated by the nanoparticles defining an electrical pathway therebetween. The system includes an electrical interconnection network connected to the electrodes of the plurality of devices configured to connect devices in series or parallel configurations. The system enables water from the reservoir to flow through distribution channels to the water-permeable material, pass through the perforation into the functionalized nanoparticles, undergo absorption at hydrophilic N-H sites, and move through the nanoparticles via capillary action from the second end toward the first end, wherein the negative zeta potential causes charge separation at the water-nanoparticle interface during transport and evaporation.
[0020] In another aspect, the present disclosure relates to a method for generating electricity from water evaporation. The method includes providing a tubular structure having first and second ends defining an internal cavity extending therebetween. The method includes positioning a second electrode at the second end including at least one perforation therethrough. The method includes disposing a water-permeable material on the second electrode to cover the perforation. The method includes filling the internal cavity through the first end with functionalized metal oxide nanoparticles that are retained by the water-permeable material, wherein the nanoparticles include metal oxide having nitrogen-containing functional groups exhibiting N-H bonds providing hydrophilic sites and having a negative zeta potential in aqueous solution. The method includes positioning a first electrode at the first end such that both electrodes are in electrical contact with and separated by the functionalized nanoparticles. The method includes contacting the water-permeable material with water from a reservoir whereby water passes through the perforation and water-permeable material into the functionalized nanoparticles. The method includes allowing water to move through the functionalized nanoparticles from the second end toward the first end via capillary action by absorption at the hydrophilic sites, wherein the negative zeta potential causes charge separation at the water-nanoparticle interface during water transport and evaporation at the first end, thereby establishing a potential difference between the electrodes.
[0021] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0022] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.
[0023] FIG. 1 illustrates an exemplary representation of a block diagram of the hydrovoltaic electricity generation system, in accordance with an embodiment of the present disclosure.
[0024] FIG. 2 illustrates an exemplary schematic representation of the functionalized metal oxide hydrovoltaic device depicting: (a) device assembly with electric double layer formation at the material/water interface and charge dynamics, (b) XRD patterns of Al₂O₃ and F-Al₂O₃, (c) FTIR spectra of Al₂O₃ and F-Al₂O₃, and (d-e) FESEM images of Al₂O₃ and F-Al₂O₃ nanoparticles, in accordance with an embodiment of the present disclosure.
[0025] FIG. 3 illustrates exemplary graphical representations of XPS analysis depicting: (a-c) high-resolution spectra of Al 2p, O 1s, and N 1s for Al₂O₃, (d-f) high-resolution spectra of Al 2p, O 1s, and N 1s for F-Al₂O₃, (g) nitrogen adsorption-desorption isotherms, and (h-i) zeta potential measurements, in accordance with an embodiment of the present disclosure.
[0026] FIG. 4 illustrates exemplary representations of electrical performance depicting: (a) schematic of water evaporation-induced power generation mechanism, (b-c) voltage and current outputs for Al₂O₃ and F-Al₂O₃ devices, (d-e) voltage/current at different load resistances and corresponding output power, and (f) performance comparison with reported hydrovoltaic devices, in accordance with an embodiment of the present disclosure.
[0027] FIG. 5 illustrates exemplary representations of device applications depicting: (a) schematic of functional group attachment onto F-Al₂O₃ nanoparticles, (b) output voltage with different numbers of devices in series, and (c) demonstration of blue LED powered by series-connected devices, in accordance with an embodiment of the present disclosure.
[0028] FIG. 6 illustrates exemplary representations of dye degradation application depicting: (a) schematic of electrochemical dye degradation setup, (b) degradation pathway of methylene blue, (c) electrochemical degradation results, and (d) visual comparison before and after treatment, in accordance with an embodiment of the present disclosure.
[0029] FIG. 7 illustrates an exemplary graphical representation of current generation depicting the transition from dry to wet state with current increase after water addition, in accordance with an embodiment of the present disclosure.
[0030] FIG. 8 illustrates an exemplary flow diagram depicting a method for generating electricity from water evaporation using functionalized metal oxide nanoparticles, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0031] The ensuing description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the ensuing description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth.
Definitions:
Functionalized Metal Oxide Nanoparticles: Metal oxide particles having nitrogen-containing functional groups attached through hydrothermal treatment with hydrazine hydrate at 90-110°C for 10-14 hours, exhibiting N-H bonds at infrared absorption peaks of 3441±10 cm⁻¹ for stretching and 1631±10 cm⁻¹ for bending, with negative zeta potential of -25 to -35 mV in aqueous solution.
Hydrovoltaic Device: An electricity generation device utilizing water evaporation-induced charge separation at the interface between functionalized metal oxide nanoparticles and water, producing electrical output through capillary action-driven water transport and electric double layer formation.
Electric Double Layer (EDL): A charge separation phenomenon occurring at the solid-liquid interface between negatively charged functionalized metal oxide nanoparticles and water molecules, where counter-positive ions (hydronium ions) accumulate near the negative surface creating a streaming potential during water flow.
Zeta Potential: The electrokinetic potential measured at the slipping plane of functionalized metal oxide nanoparticles in aqueous suspension, with Al₂O₃ exhibiting -4.88 mV and F-Al₂O₃ exhibiting -30.8 mV, indicating surface charge characteristics affecting ion selectivity and charge separation efficiency.
Surface Area Enhancement: The increase in specific surface area from 39.7 m²/g for pristine Al₂O₃ to 91.9 m²/g for functionalized Al₂O₃ achieved through hydrazine hydrate treatment, providing increased water-material interaction sites for enhanced charge collection.
[0032] An aspect of the present disclosure relates to a hydrovoltaic electricity generation system including functionalized metal oxide nanoparticles positioned within tubular structures of a water distribution network, the nanoparticles include nitrogen-containing functional groups providing hydrophilic sites for enhanced water interaction. The system includes a water reservoir supplying continuous water flow through distribution channels to multiple hydrovoltaic devices. The system includes tubular structures with internal cavities containing 0.75-1.5 g of functionalized nanoparticles arranged for optimal water transport. The system includes perforated electrodes with 0.3-0.7 mm diameter holes covered by water-permeable cotton material. The system includes aluminum first electrodes and copper second electrodes separated by 8-12 mm distance within the tubular structure. The system includes an electrical interconnection network enabling series and parallel configurations for voltage and current scaling. The system includes processing capabilities for electrochemical dye degradation utilizing generated electricity. The system includes performance metrics achieving 1.08 V open-circuit voltage and 80 μA short-circuit current representing highest reported values for Al₂O₃-based hydrovoltaic devices.
[0033] Various embodiments of the present disclosure are described using FIGs. 1 to 8.
[0034] FIG. 1 illustrates an exemplary representation of a block diagram of the hydrovoltaic electricity generation system, in accordance with an embodiment of the present disclosure.
[0035] In an embodiment, referring to FIG. 1, the system (100) for generating electricity from water evaporation can include a water reservoir (101) providing continuous water supply through gravity-fed or pumped distribution, water-permeable material (102) including cotton fibers enabling uniform water uptake, a second electrode (103) with multiple perforations allowing controlled water passage, functionalized metal oxide nanoparticles (104) filling the tubular cavity with optimized loading, a first electrode (105) collecting generated charges at the evaporation zone, and operational processes including capillary action (106), charge separation (107), and water evaporation (108) producing electrical output (109) of 1.08 V and 80 μA.
[0036] In an embodiment, the water reservoir (101) can include containers holding deionized water to maintain consistent water quality for optimal device performance.
[0037] In an embodiment, the water reservoir (101) can be implemented in the system (100) to establish continuous water supply ensuring uninterrupted electricity generation. The reservoir (101) can include storage capacity sufficient for extended operation periods without refilling. The reservoir (101) can be positioned at elevated height enabling gravity-driven water flow eliminating need for external pumps. The reservoir can connect to distribution channels through flow control valves regulating water delivery rate. The reservoir configuration can accommodate various water sources including distilled, deionized, or tap water depending on application requirements.
[0038] In an embodiment, the reservoir (101) can include, but are not limited to, plastic containers, glass vessels, metal tanks, and flexible bladders, to provide chemical compatibility with water and system components.
[0039] In an embodiment, the functionalized metal oxide nanoparticles (104) can be implemented in the system (100) to enable water evaporation-induced electricity generation through enhanced hydrophilicity and charge separation. The nanoparticles (104) can function by providing high surface area for increased water-material interaction. The nanoparticles (104) can include metal oxides treated with hydrazine hydrate creating N-H functional groups. For Al₂O₃, treatment with 0.5 ml hydrazine hydrate per 4 g oxide at 100°C for 12 hours created N-H functional groups confirmed by FTIR peaks at 3441 cm⁻¹ and 1631 cm⁻¹, achieving surface area of 91.9 m²/g. The nanoparticles (104) can exhibit mesoporous structure with 271 nm average pore width facilitating capillary water transport. The nanoparticles (104) can demonstrate negative zeta potential of -30.8 mV for F-Al₂O₃ ensuring positive ion selectivity during charge separation.
[0040] In an embodiment, systematic optimization of the hydrothermal treatment conditions revealed that the temperature range of 90-110°C and treatment time of 10-14 hours consistently produced functionalized metal oxide nanoparticles with desired properties. While the optimal conditions of 100°C for 12 hours yielded Al₂O₃ with 91.9 m²/g surface area and -30.8 mV zeta potential, variations within the claimed ranges maintained functionality. At 90°C, extended treatment time of 14 hours was required to achieve complete functionalization, resulting in surface area exceeding 80 m²/g. At 110°C, reduced treatment time of 10 hours was sufficient due to enhanced reaction kinetics, producing surface area approaching 100 m²/g. The negative zeta potential varied from -25 mV at lower functionalization temperatures to -35 mV at higher temperatures, with all values within this range demonstrating effective charge separation capability.
[0041] In an embodiment, the functionalization process was successfully applied to various metal oxides beyond Al₂O₃. Bi₂O₃ nanoparticles functionalized using identical hydrothermal conditions (4 g oxide, 50 ml DI water, 0.5 ml hydrazine hydrate) showed enhanced performance after functionalization, as evidenced by increased voltage and current outputs. MgO nanoparticles similarly demonstrated improved hydrovoltaic performance post-functionalization. The XRD patterns confirmed retention of crystalline structure while FTIR analysis revealed successful N-H functionalization across all tested metal oxides. This validates the broad applicability of the functionalization approach within the claimed metal oxide group.
[0042] In an embodiment, the mechanism of porosity enhancement through hydrazine hydrate treatment involves reductive etching at defect sites and grain boundaries. The treatment creates voids through removal of aluminum ions while decomposition of hydrazine hydrate releases gaseous byproducts (nitrogen and ammonia) that escape the matrix, leaving behind pores. This controlled chemical modification increased surface area from 39.7 m²/g for pristine Al₂O₃ to values ranging from 80-100 m²/g depending on treatment conditions, with mesoporous structures exhibiting pore widths of 271-311 nm facilitating enhanced capillary water transport.
[0043] In an embodiment, the nanoparticles (104) can include, but are not limited to, Al₂O₃, Bi₂O₃, MgO, TiO₂, ZnO, and combinations thereof, to provide varied surface properties and performance characteristics for hydrovoltaic applications.
[0044] In an embodiment, the tubular structure (110) can be implemented in the system (100) to act as the structural framework housing functionalized nanoparticles and defining water flow pathway. Testing with 0.5 g, 0.75 g, 1.0 g, and 1.25 g loadings revealed optimal performance at 1.0 g, generating 1.08 V and 80 μA. Lower loadings of 0.5 g and 0.75 g produced 0.24 V and 0.63 V respectively, while 1.25 g yielded 0.92 V, demonstrating the importance of optimal loading within the 0.75-1.5 g range. The structure (110) can maintain 30 mm length and 3 mm wall thickness dimensions optimized through systematic testing. The structure (110) can position electrodes at 10 mm separation distance enabling efficient charge collection. The structure (110) can facilitate vertical water transport enhancing evaporation rate compared to horizontal configurations.
[0045] In an embodiment, dimensional optimization of the tubular structure confirmed functional operation across the claimed ranges. While 30 mm length provided optimal 1.08 V output, tubes ranging from 20-40 mm all generated measurable electricity exceeding 0.8 V, validating the functional range. The inner diameter range of 5-8 mm was established based on capillary flow requirements, with 3 mm providing optimal balance between water transport and evaporation. Nanoparticle loading studies demonstrated that amounts from 0.75-1.5 g all produced functional devices, with performance variations reflecting the trade-off between active material quantity and flow resistance. Excessive loading beyond 1.0 g caused denser packing that reduced water penetration, explaining the voltage decrease to 0.92 V at 1.25 g loading.
[0046] In an embodiment, the structure (110) can include one or more features to enhance water flow including internal baffles directing water distribution, surface texturing promoting uniform wetting, and thermal insulation maintaining consistent operating temperature.
[0047] In an embodiment, the one or more features configured within the tubular structure (110) can be designed to optimize water transport dynamics and charge collection efficiency. If upon detection water flow rate exceeds predetermined threshold causing incomplete charge separation, the internal baffles can be operable to automatically regulate flow velocity. The tubular structure (110) can ensure optimal residence time for maximum electricity generation.
[0048] In an embodiment, the second electrode (103) can be implemented to serve triple functions as water entry interface, negative charge collector, and structural support for the nanoparticles. The electrode (103) can be configured with multiple 0.5 mm diameter perforations distributed across surface area, selected from extensive testing of the 0.3-0.7 mm range. The copper electrode (103) serves as a reliable support, effectively preventing the Al₂O₃ from falling out during experimental procedures, with cotton material covering the bottom electrode for water uptake through the perforations. Upon water contact through perforations via the cotton covering, the electrode (103) can facilitate uniform water distribution into nanoparticle bed. Perforation diameters below 0.3 mm restricted water flow while above 0.7 mm caused uneven distribution, establishing the functional range.
[0049] In an embodiment, the first electrode (105) can provide positive charge collection at the evaporation zone completing the electrical circuit. The electrode (105) can include aluminum material selected for chemical stability and cost-effectiveness. The electrode positioning at tube top can maximize exposure to evaporating water enhancing charge collection efficiency. The electrode configuration can ensure electrical contact with functionalized nanoparticles throughout operational lifetime.
[0050] In an embodiment, electrode separation optimization revealed functional electricity generation across the 8-12 mm range. Testing with symmetric aluminum electrodes at 10 mm separation produced only 0.32 V and 10 μA, while asymmetric Al-Cu configuration achieved 1.08 V and 80 μA, demonstrating the importance of electrode material selection. The 10 mm separation provided optimal balance between charge gradient development and internal resistance. Separations of 8 mm and 12 mm maintained functionality with slightly reduced performance, generating voltages exceeding 0.95 V, confirming the operational range. The asymmetric electrode configuration utilizing aluminum (first electrode) and copper (second electrode) materials created enhanced potential difference contributing to superior performance.
[0051] In an embodiment, the water-permeable material (102) can enable controlled water passage into the device while the second electrode (103) prevents nanoparticle loss. The material (102) can include cotton fibers specifically covering the second electrode (103) to facilitate water uptake through the perforations. The cotton material can demonstrate hydrophilic properties facilitating water uptake through capillary forces. The material placement covering the perforated copper electrode can ensure uniform water distribution preventing channeling effects, while the copper electrode itself serves as a reliable support structure preventing the functionalized metal oxide nanoparticles (104) from falling out during operation.
[0052] In an embodiment, charge separation mechanism, fundamental to hydrovoltaic operation, can occur at the water-nanoparticle interface through electric double layer formation. The mechanism can involve attraction of positive hydronium ions to negatively charged nanoparticle surfaces creating potential gradient. The continuous water flow through capillary action can maintain non-equilibrium conditions necessary for sustained charge separation. The negative zeta potential of -30.8 mV can ensure strong electrostatic interactions enhancing charge separation efficiency.
[0053] In an embodiment, the electrical interconnection network can enable flexible system configuration for various application requirements. The network can connect first electrode of one device to second electrode of adjacent device for series operation increasing voltage output. The network can alternatively connect corresponding electrodes of multiple devices in parallel configuration enhancing current output. The interconnection system can accommodate modular expansion allowing system scaling based on power requirements.
[0054] In an embodiment, the system (100) can demonstrate validated performance metrics ensuring reliable electricity generation. The open-circuit voltage of 1.08 V can represent 80% improvement over non-functionalized Al₂O₃ devices. The short-circuit current of 80 μA can exceed all previously reported values for Al₂O₃-based hydrovoltaic systems. The maximum power output of 12 μW at 20 kΩ load resistance can enable practical applications. The stable operation over 6000 seconds can confirm long-term reliability for continuous power generation.
[0055] FIG. 2 illustrates an exemplary schematic representation of the functionalized metal oxide hydrovoltaic device depicting: (a) device assembly with electric double layer formation at the material/water interface and charge dynamics, (b) XRD patterns of Al₂O₃ and F-Al₂O₃, (c) FTIR spectra of Al₂O₃ and F-Al₂O₃, and (d-e) FESEM images of Al₂O₃ and F-Al₂O₃ nanoparticles, in accordance with an embodiment of the present disclosure.
[0056] In an embodiment, referring to FIG. 2, illustrating an exemplary representation of device structure and characterization (200) for the hydrovoltaic system (100). Panel (a) depicts electric double layer formation showing water molecules interacting with functionalized nanoparticle surfaces creating distinct charge separation zones. Upon water contact with F-Al₂O₃ surfaces, negative charges can attract positive hydronium ions forming structured layers. This charge organization can remain critical for streaming potential generation during water transport. Panel (b) shows XRD patterns confirming crystalline structure with peaks at 32.5°, 37.5°, 39.5°, 45.4°, and 67.2° matching Al₂O₃ reference patterns. Panel (c) displays FTIR spectra revealing N-H functionalization at 3441 cm⁻¹ and 1631 cm⁻¹. Panels (d-e) present FESEM images showing morphological transformation from larger Al₂O₃ flakes to smaller porous F-Al₂O₃ structures.
[0057] FIG. 3 illustrates exemplary graphical representations of XPS analysis depicting: (a-c) high-resolution spectra of Al 2p, O 1s, and N 1s for Al₂O₃, (d-f) high-resolution spectra of Al 2p, O 1s, and N 1s for F-Al₂O₃, (g) nitrogen adsorption-desorption isotherms, and (h-i) zeta potential measurements, in accordance with an embodiment of the present disclosure.
[0058] In an embodiment, referring to FIG. 3 illustrate comprehensive surface chemistry analysis (300) for system (100) demonstrating successful functionalization through nitrogen incorporation. XPS analysis confirmed nitrogen attachment with N 1s peaks at 399.6 eV (N-H) and 395.5 eV (N-H₂) bonds. BET measurements showed surface area of 39.7 m²/g for pristine Al₂O₃ increasing to 91.9 m²/g for F-Al₂O₃ under optimal conditions (100°C, 12 hours). The functionalization process consistently produced surface areas within the 80-100 m²/g range across different treatment conditions, with lower temperatures yielding areas near 80 m²/g and higher temperatures approaching 100 m²/g. Zeta potential measurements revealed -4.88 mV for Al₂O₃ and -30.8 mV for F-Al₂O₃. The negative zeta potential enhancement correlated with functionalization temperature, ranging from -25 mV to -35 mV across the treatment conditions, ensuring electrostatic stability and positive ion selectivity throughout the operational range.
[0059] FIG. 4 illustrates exemplary representations of electrical performance depicting: (a) schematic of water evaporation-induced power generation mechanism, (b-c) voltage and current outputs for Al₂O₃ and F-Al₂O₃ devices, (d-e) voltage/current at different load resistances and corresponding output power, and (f) performance comparison with reported hydrovoltaic devices, in accordance with an embodiment of the present disclosure.
[0060] In an embodiment, referring to FIG. 4 illustrate electrical output analysis (400) for system (100) validating superior power generation capabilities. At panel (a) schematic representation shows water evaporation mechanism under ambient conditions. The process demonstrates water uptake through capillary action followed by evaporation-induced charge separation. Panel (b) compares voltage outputs with F-Al₂O₃ achieving 1.08 V versus 0.6 V for pristine Al₂O₃. At panel (c) current measurements reveal 80 μA for F-Al₂O₃ compared to 50 μA for Al₂O₃. The system (100) demonstrates 60% current enhancement through functionalization. At panel (d) voltage-current relationships across load resistances from 100 Ω to 100 kΩ establish operating characteristics. Panel (e) identifies optimal power output of 12 μW at 20 kΩ load resistance. At panel (f) performance comparison positions current system as achieving highest current among reported Al₂O₃ devices.
[0061] In an embodiment, the system (100) can handle varying operational conditions by detecting changes in ambient humidity, automatically adjusting water flow rates, maintaining stable electrical output through feedback control, optimizing load matching for maximum power transfer, enabling continuous operation without manual intervention, ensuring consistent performance across environmental variations, and allowing integration with energy storage systems.
[0062] FIG. 5 illustrates exemplary representations of device applications depicting: (a) schematic of functional group attachment onto F-Al₂O₃ nanoparticles, (b) output voltage with different numbers of devices in series, and (c) demonstration of blue LED powered by series-connected devices, in accordance with an embodiment of the present disclosure.
[0063] In an embodiment, referring to FIG. 5 illustrate practical applications (500) for system (100) demonstrating real-world utility beyond laboratory conditions. Panel (a) shows molecular mechanism of amine group attachment to Al₂O₃ surface through chemisorption. The functionalization process creates covalent Al-N bonds enhancing surface properties. Panel (b) demonstrates voltage scaling with series connections achieving 1.08 V, 1.9 V, 2.74 V, and 3.75 V for one through four devices respectively. The linear voltage addition confirms minimal connection losses. Panel (c) photographs blue LED illumination powered by four series-connected devices validating practical power generation. The LED operation at >2.2 V and 100 μA demonstrates sufficient power for electronic applications.
[0064] FIG. 6 illustrates exemplary representations of dye degradation application depicting: (a) schematic of electrochemical dye degradation setup, (b) degradation pathway of methylene blue, (c) electrochemical degradation results, and (d) visual comparison before and after treatment, in accordance with an embodiment of the present disclosure.
[0065] In an embodiment, referring to FIG. 6 illustrate environmental remediation capability (600) for system (100) extending functionality beyond power generation. Panel (a) depicts electrochemical setup connecting hydrovoltaic device to graphite anode and platinum cathode in dye solution. The generated electricity drives oxidation-reduction reactions producing reactive species. Panel (b) illustrates methylene blue degradation pathway initiated by hydroxyl radicals breaking N-CH₃ bonds. The sequential degradation produces intermediates before complete mineralization to CO₂, H₂O, SO₄²⁻, and NO₃⁻. Panel (c) shows UV-Vis spectra comparing initial 5 ppm solution with treated sample after 24 hours. The 665 nm absorption peak reduction indicates successful degradation. Panel (d) provides visual evidence through solution color change from blue to clear confirming dye removal effectiveness.
[0066] FIG. 7 illustrates an exemplary graphical representation of current generation depicting the transition from dry to wet state with current increase after water addition, in accordance with an embodiment of the present disclosure.
[0067] In an embodiment, referring to FIG. 7 illustrate temporal response characteristics (700) for system (100) confirming water-dependent operation mechanism. The current monitoring over 600 seconds reveals distinct operational phases with zero current in dry state. At 130 seconds before water addition, device remains inactive confirming water requirement. Upon water introduction, current increases following exponential pattern reaching 60 μA steady-state within 400 seconds. The 270-second activation time from water contact to stable output characterizes device response kinetics. This behavior validates electrokinetic mechanism requiring continuous water flow for sustained electricity generation.
[0068] FIG. 8 illustrates an exemplary flow diagram depicting a method for generating electricity from water evaporation using functionalized metal oxide nanoparticles, in accordance with an embodiment of the present disclosure.
[0069] In an embodiment, referring to FIG. 8 illustrate step-by-step fabrication and operation process (800) for system (100) outlining systematic device assembly methodology. At step (802) providing tubular structure establishes containment framework. The process positions perforated second electrode at step (804). The system (100) disposes water-permeable material at step (806) covering perforations. At step (808) the system (100) fills cavity with functionalized nanoparticles containing N-H bonds. At step (810) the system (100) positions first electrode completing assembly. The system initiates water contact at step (812) beginning capillary transport. At step (814) the system allows water movement through nanoparticles via hydrophilic sites. The system achieves charge separation at step (816) through electric double layer formation. At step (818) the system (100) generates electrical output of 1.08 V and 80 μA demonstrating successful operation.
[0070] In an embodiment, the system (100) can handle varying power requirements by detecting load conditions, automatically configuring series/parallel connections, generating scaled voltage/current outputs, activating appropriate device numbers, enabling modular power generation, ensuring efficient energy utilization, and allowing customized power delivery for specific applications.
[0071] The described disclosure presents an advanced hydrovoltaic electricity generation system (100) integrated with functionalized metal oxide nanoparticles can offer several novel features that distinguish it from existing water evaporation technologies. The system (100) can automatically generate electricity when water contacts functionalized nanoparticles, enabling self-powered operation. The functionalized Al₂O₃ nanoparticles (104) can be strategically filled within tubular structures (110) along with optimized electrode configuration (103, 105) that coordinate the entire electricity generation process. During operation, combination of enhanced capillary action and efficient charge separation can ensure maximum power output across the device. The automated operation of system (100) can ensure consistent electricity generation without requiring external power sources. The generated electricity can effectively power electronic devices and enable environmental remediation applications.
[0072] In an exemplary embodiment, the system (100) can operate within validated performance metrics to ensure reliable electricity generation across various applications. The system (100) can demonstrate voltage stability with coefficient of variation below 10% across multiple devices representing consistent manufacturing quality. The functionalization process can increase surface area by 131% from 39.7 to 91.9 m²/g enhancing water interaction capacity. The mean corrected current density of 26.7 μA/cm² compared to typical values below 10 μA/cm² can indicate superior charge collection efficiency. The system (100) can maintain continuous operation over 6000 seconds without performance degradation. These validated performance metrics make the system (100) practical, efficient, and effective for sustainable energy harvesting applications.
[0073] While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter to be implemented merely as illustrative of the disclosure and not as limitation.
[0074] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0075] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0076] Moreover, in interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0077] While the foregoing describes various embodiments of the proposed disclosure, other and further embodiments of the proposed disclosure may be devised without departing from the basic scope thereof. The scope of the proposed disclosure is determined by the claims that follow. The proposed disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
EXAMPLES
EXAMPLE 1: Optimal Device Performance with Functionalized Al₂O₃
[0078] Aluminum oxide nanoparticles were functionalized through hydrothermal treatment by adding 4 grams of Al₂O₃ to 50 ml deionized water with 0.5 ml hydrazine hydrate in a Teflon-lined autoclave heated at 100°C for 12 hours. This represents the optimal point within the broader functional range of 90-110°C for 10-14 hours. After washing and drying at 80°C, characterization confirmed N-H functional groups at 3441 cm⁻¹ (stretching) and 1631 cm⁻¹ (bending) via FTIR spectroscopy, with the ±10 cm⁻¹ tolerance accounting for normal instrumental variations. The surface area increased from 39.7 m²/g to 91.9 m²/g, falling within the functional range of 80-100 m²/g achievable through varied treatment conditions. Zeta potential changed from -4.88 mV to -30.8 mV, representing the midpoint of the -25 to -35 mV operational range.
[0079] A hydrovoltaic device was fabricated using a silicon tube (30 mm length, 3 mm thickness) with a perforated copper electrode (0.5 mm holes) at the bottom. The copper electrode served as a reliable support, effectively preventing the Al₂O₃ from falling out during the experimental procedures, and cotton was used to cover this bottom electrode for water uptake through the perforations. The tube was filled with 1.0 g of F-Al₂O₃ nanoparticles, and an aluminum electrode was positioned at the top with 10 mm electrode separation. The device was connected to a deionized water reservoir.
[0080] The optimized device generated 1.08 V open-circuit voltage and 80 μA short-circuit current, exceeding all previously reported Al₂O₃ hydrovoltaic devices. Maximum power output of 12 μW occurred at 20 kΩ load resistance. Four devices connected in series produced 3.75 V, successfully powering a commercial blue LED (>2.2 V, 100 μA). The device maintained stable output over 6000 seconds of continuous operation.
EXAMPLE 2: Electrochemical Methylene Blue Dye Degradation
[0081] The hydrovoltaic device was utilized for electrochemical dye degradation by connecting it to a 100 ml beaker containing 5 ppm methylene blue solution with graphite anode and platinum cathode separated by 1 cm. The generated electricity from the hydrovoltaic device powered the degradation process without external power sources.
[0082] UV-Vis spectroscopy monitoring showed significant reduction of the 665 nm absorption peak after 24 hours treatment, with the solution transforming from blue to clear. The degradation mechanism involved hydroxyl radical generation breaking N-CH₃ bonds, followed by cleavage of C-N and C-S bonds producing intermediates, ultimately mineralizing to CO₂, H₂O, SO₄²⁻, and NO₃⁻.
[0083] Testing with multiple dye concentrations (1, 2.5, 5, 7.5, and 10 ppm) confirmed effectiveness across different pollution levels, with lower concentrations requiring proportionally shorter treatment times. This demonstration validated the dual functionality of the hydrovoltaic system for both sustainable power generation and environmental remediation applications.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0084] The present invention achieves unprecedented electrical output of 1.08 V open-circuit voltage and 80 μA short-circuit current from water evaporation, representing 80% voltage improvement and 60% current enhancement over non-functionalized Al₂O₃ devices, enabling practical power generation for electronic devices without external energy sources.
[0085] The functionalized metal oxide nanoparticles demonstrate 131% increase in surface area from 39.7 to 91.9 m²/g and enhanced negative zeta potential of -30.8 mV, providing superior water-material interaction and charge separation efficiency that translates to stable power generation over 6000 seconds of continuous operation.
, Claims:1. A system for generating electricity from water evaporation (100) comprising:
a water distribution system comprising a main water reservoir (101) and distribution channels extending therefrom;
a plurality of hydrovoltaic power generation devices fluidly connected to the distribution channels, each device comprising:
a tubular structure (110) defining an internal cavity extending from a second end to a first end,
a second electrode (103) positioned at the second end of the tubular structure (110), the second electrode (103) having at least one perforation therethrough,
a water-permeable material (102) disposed on the second electrode (103) covering the at least one perforation, the water-permeable material (102) being in fluid communication with the distribution channels for receiving water therefrom,
functionalized metal oxide nanoparticles (104) filling the internal cavity and supported by the water-permeable material (102), the functionalized metal oxide nanoparticles (104) comprising metal oxide nanoparticles having nitrogen-containing functional groups with N-H bonds providing hydrophilic sites and having a negative zeta potential of -25 to -35 mV in aqueous solution,
a first electrode (105) positioned at the first end of the tubular structure (110) and in electrical contact with the functionalized metal oxide nanoparticles (104), the first electrode (105) and the second electrode (103) being separated by the functionalized metal oxide nanoparticles (104) thereby defining an electrical pathway therebetween;
an electrical interconnection network connected to the first and second electrodes (105, 103) of the plurality of devices, the network configured to connect the first electrode (105) of one device to the second electrode (103) of an adjacent device for series configuration, or to connect corresponding electrodes of multiple devices for parallel configuration;
wherein water from the main water reservoir (101) flows through the distributionn channels to the water-permeable material (102) of each device, passes through the at least one perforation and through the water-permeable material (102) into the functionalized metal oxide nanoparticles (104), is absorbed by the hydrophilic N-H sites and moves through the functionalized metal oxide nanoparticles (104) via capillary action (106) from the second end toward the first end, and wherein the negative zeta potential of the functionalized metal oxide nanoparticles (104) causes charge separation (107) at an interface between the functionalized metal oxide nanoparticles (104) and the water during transport through the functionalized metal oxide nanoparticles (104) and evaporation (108) at the first end.
2. The system as claimed in claim 1, wherein the metal oxide nanoparticles are selected from the group consisting of Al₂O₃, Bi₂O₃, MgO, TiO₂, ZnO, and combinations thereof.
3. The system as claimed in claim 1, wherein the nitrogen-containing functional groups are formed by hydrothermal treatment of the metal oxide nanoparticles with hydrazine hydrate at a temperature of 90-110°C for 10-14 hours.
4. The system as claimed in claim 1, wherein the functionalized metal oxide nanoparticles (104) have a surface area of 80-100 m²/g and the negative zeta potential is in the range of -25 to -35 mV in deionized water.
5. The system as claimed in claim 1, wherein the tubular structure (110) has a length of 20-40 mm and an inner diameter of 5-8 mm, and wherein the internal cavity contains 0.75-1.5 g of the functionalized metal oxide nanoparticles (104).
6. The system as claimed in claim 1, wherein the at least one perforation comprises a plurality of perforations, each perforation having a diameter of 0.3-0.7 mm, and wherein the water-permeable material (102) comprises cotton fibers covering the second electrode (103) for water uptake through the perforations, with the second electrode (103) serving as a support to prevent the functionalized metal oxide nanoparticles (104) from falling out.
7. The system as claimed in claim 1, wherein the first electrode (105) comprises aluminum and the second electrode (103) comprises copper, the first electrode (105) and the second electrode (103) being separated by a distance of 8-12 mm within the tubular structure (110).
8. The system as claimed in claim 1, wherein the N-H bonds of the nitrogen-containing functional groups exhibit infrared absorption peaks at 3441±10 cm⁻¹ for N-H stretching and 1631±10 cm⁻¹ for N-H bending.
9. The system as claimed in claim 1, further comprising a water reservoir (101) in fluid communication with the water-permeable material (102), wherein the water reservoir (101) maintains continuous water supply to the water-permeable material (102) during operation of the device.
10. A method for generating electricity from water evaporation comprising:
providing (802) a tubular structure (110) having a first end and a second end opposite to said first end, said tubular structure (110) defining an internal cavity extending from said second end to said first end;
positioning (804) a second electrode (103) at said second end of said tubular structure (110), said second electrode (103) comprising at least one perforation therethrough;
disposing (806) a water-permeable material (102) on said second electrode (103) to cover said at least one perforation;
filling (808) said internal cavity through said first end with functionalized metal oxide nanoparticles (104), said functionalized metal oxide nanoparticles (104) being retained within said cavity by said water-permeable material (102), said functionalized metal oxide nanoparticles (104) comprising metal oxide nanoparticles having nitrogen-containing functional groups attached thereto, said nitrogen-containing functional groups exhibiting N-H bonds that provide hydrophilic sites, said functionalized metal oxide nanoparticles (104) having a negative zeta potential in aqueous solution;
positioning (810) a first electrode (105) at said first end of said tubular structure (110) such that said first electrode (105) and said second electrode (103) are in electrical contact with said functionalized metal oxide nanoparticles (104) and are separated by said functionalized metal oxide nanoparticles (104);
contacting (812) said water-permeable material (102) with water from a water reservoir (101), whereby said water passes through said at least one perforation and through said water-permeable material (102) into said functionalized metal oxide nanoparticles (104);
allowing (814) said water to move through said functionalized metal oxide nanoparticles (104) from said second end toward said first end via capillary action (106) by absorption at said hydrophilic sites;
wherein said negative zeta potential of said functionalized metal oxide nanoparticles (104) causes charge separation (107) at an interface between said functionalized metal oxide nanoparticles (104) and said water during transport of said water through said functionalized metal oxide nanoparticles (104) and evaporation (108) of said water at said first end, thereby establishing a potential difference between said first electrode (105) and said second electrode (103).