Preparation And Exploration Of Silver-based Oxygen Reduction Catalysts By Electrochemical Solid Phase Reduction

Alkaline fuel cells?AFCs?have attracted great attention because of their simple structure,high energy conversion efficiency,easy portability and environmental friendliness.The high cost of precious metal electrocatalyst has become an important factor restricting the commercialization of fuel cells.Therefore,it is of great significance to develop stable and efficient electrocatalysts to reduce battery cost and promote the development of fuel cell technology.Silver as a fuel cell oxygen reduction ORR catalyst has the advantages of low raw material cost,abundant reserves and long life,which is an important development direction of alkaline proton exchange membrane fuel cells.Here,this paper explored and prepared a series of high performance silver-based catalysts,which greatly improved the catalytic properties of Ag.At the same time,the evolution of the morphology of porous materials was also explored.And some factors in the process and the results of the polarization test were explored.The results are as follows:?1?The precursor AgBr/C was prepared by impregnation precipitation method,then the precursor was electrochemically reduced to obtain Ag/C,and its catalytic activity for oxygen reduction reaction was tested.The conventional method was used to prepare Ag/C to compare their oxygen reduction reaction.Catalytic properties.The half-wave potentialE_1/2 is 100 mv higher than the conventional Ag/C and 40 mv smaller than Pt/C,indicating that the performance of the silver catalyst obtained by the electrochemical method is greatly improved.?2?Precursor cubic AgBr was prepared by organic precipitation and precipitation,and then electrochemical solid phase reduction cubic porous silver oxide reduction catalyst.SEM showed that there were three-dimensional porous structure and continuous in the nanoporous silver cube sample.The ligament,the pore size of the porous silver is 30-80 nm,and the nature of the high-index face defect structure can also be seen in the HRTEM image.Electrochemically,the initial potential of the porous Ag cube is close to Pt,and the half-wave potential is 860 mV,which is only a few ten millivolts lower than the commercial Pt/C catalyst,and is much higher than the ordinary silver nanowire.100 mv.After tens of thousands of cycles of cubic porous silver,the catalytic performance is still very good,indicating that it is stable enough.There is also a reason for exploring the electrochemical formation of porosity by the potential and the solubility of the electrolyte,and the mechanism of the porous structure by the theory of permeation is presumed.?3?The precursor AgI was synthesized by direct precipitation,and then electrochemically reduced to obtain a foamed Ag nanowire catalyst having a twin structure.Its specific area activity was 11.5 mA/cm2 in the 0.85 V electrochemical test,and the mass activity was 8.6 A/mg,which was doubled compared with the catalytic performance of the C-Ag nanowire ORR.The increase in mass activity was found to be due to an increase in effective electrochemical surface area and an increase in area activity.