Study On Preparation And Photocatalytic H₂O₂ Fuel Cells Performance Of G-C₃N₄ Supported By Nano Silver

The conversion of solar power to electricity is an effective way to solve the issues of energy crisis and environmental pollution.The photocatalyst was used to oxidize H₂O and synthesize H₂O₂ as fuel to construct the cell.Compared with O₂ reduction synthesis of H₂O₂,the former has the advantages of economy and wide source of raw materials.A self-supplying H₂O₂ fuel cell is constructed using photocatalyst as electrode material,which can store chemical energy in the presence of sunlight and convert chemical energy into electricity in dark conditions.Photocatalyst,as an anode for synthesis of H₂O₂,is considered to be one of the key factors in determining cell performance,among which graphitic phase carbon nitride（g-C₃N₄）has attracted the attention of researchers due to its moderate band gap,high stability and low cost.Through the noble metal localized surface plasmon resonance（LSPR）,the absorption of photon energy of g-C₃N₄ can be enhanced,and the recombination rate of electron and hole can be reduced,etc.In this paper,two g-C₃N₄ composite photocatalysts supported by Ag nanoparticles were designed and prepared,and used as electrode materials for photocatalytic H₂O₂ fuel cells.Specific research contents are as follows:（1）A kind of porous g-C₃N₄（pg-C₃N₄）with larger specific surface area was prepared by using melamine and ammonia water as raw materials through high-temperature thermal polymerization.Ag/pg-C₃N₄ composite photocatalyst was obtained by in-situ reduction method by loading Ag nanocubes（Ag NCs）on pg-C₃N₄.And it is applied to photocatalytic H₂O₂ fuel cells.A nickel mesh coated with 5%-Ag/pg-C₃N₄ and the carbon paper loaded by g-C₃N₄-mixed iron phthalocyanine(Fe^IIPc)used as the photoanode and cathode,respectively,were constructed to the photocatalytic H₂O₂ fuel cell,which exhibits the maximum power density of0.744 m W cm^-2 in the 0.1 M HCl solution under AM 1.5G sunlight.This 5%-Ag/pg-C₃N₄-based cell has around 3.1 times enhancement in power density compared with the pristine g-C₃N₄-based cell.And the solar-to-electrical conversion efficiency（SECE）of above cell is further calculated to be 0.416%.In addition,the photocatalytically generated H₂O₂（chemical energy）can be stored in water after 2 h irradiation,and then be used as fuel by the connection of two electrodes in the dark,yielding a specific capacitance of 4780 m F cm^-2.As the anode material of photocatalytic H₂O₂ fuel cells,5%-Ag/pg-C₃N₄-4 composites exhibit excellent photoelectric conversion and energy storage capabilities.（2）A kind of Ag/CCN composite photocatalyst supported by Ag nanoparticles（Ag NPs）was synthesized by high temperature thermal polycondensation with melamine and m-phenylenediamine（MPD）as raw materials.Combined with the introduction of graphitic carbon units and LSPR effect,5%-Ag/CCN has the advantages of narrow band gap,wide optical absorption range and low electron hole recombination rate.The maximum power density of5%-Ag/CCN-based H₂O₂ fuel cell is 1.195 m W cm^-2,which is about 2.4 times that of g-C₃N₄-based cell,and the SECE is 0.886%.The specific capacitance produced after irradiation for 2 h can reach 6860 m F cm^-2.This work has produced a high performance 5%-Ag/CCN material that exhibits excellent optical storage capability in the field of photocatalytic H₂O₂ fuel cells.