Research On Composite Electrocatalyst Based On Silver Nanowires

The technology of water splitting has been widely studied due to the problems of energy shortage and environmental pollution.Hydrogen evolution reaction?HER?and oxygen evolution reaction?OER?are two half reaction processes in the water splitting.Nowadays,Pt/C is considered to be the best HER electrocatalyst while IrO₂ and RuO₂ are considered to be the best electrocatalysts for OER.However,because of the high cost and the scarcity of noble metal catalysts,the practical application of water splitting technology has been limited.Therefore,the preparation of non-Pt and low-Pt electrocatalysts has attracted more attention.However,long preparation time and complex preparation strategies are needed to obtain electrocatalysts with high performance.In this work,we synthesize a series of composite nanomaterials based on silver nanowires and applied them to the study of electrocatalytic properties.The main contents are as follows:1.We prepared an electrocatalyst with interface composition of Pd-C/N at high temperature by modifying nitrogen-containing polymer with silver nanowires and combining Pd nanoparticles.In detail,Pd nanoparticles?NPs?with a diameter of 4 nm were adsorbed on the surface of AgNWs coated with dopamine and then calcined at high temperature,and then the Pd supported C-N doped Ag nanowires?Pd-C/N-AgNWs?were obtained.The effect of calcination temperature on the catalytic performance was studied in detail.It was found that the Pd-C/N interface formed during the calcination process was helpful in improving the HER catalytic performance.The overpotential of the obtained catalysts was just 111 mV at-10mA/cm² and the Tafel slope of the catalysts was 64 mV/dec,which was comparable to that of other Pd based HER electrocatalysts.2.Furthermore,the mixed NPs that containing AgNPs and PdNPs were loaded on the surface of dopamine coated AgNWs and another kind of N-dope-AgPd@AgNWs was obtained after sintered at high temperature.The amount of active sites of the composite nanowires for catalyzing HER could be adjusted by controlling the initial molar ratio of the two metals.The characterization for electrocatalytic performance showed that the obtained catalyst showed excellent catalytic activity with 109 mV overpotential to afford a current density of-10 mA/cm²and a Tafel slope of 60 m V/dec and good stability when the initial molar ration of Ag to Pd was1:1.Such method for synthesizing AgNWs based electrocatalysts not only improves the HER catalytic performance,but also further reduces the content of precious metal.3.We have proposed a simple method for the synthesis of AgNWs/CoFe hydrotalcite composites for electrocatalysing OER by using AgNWs networkas the substrate and Co?NO₃?₂·6H₂O,Fe?NO₃?₃·9H₂O as the non-noble metal source.After electrochemical deposition,CoFe hydrotalcite was formed on the surface of silver thin films and AgNWs/CoFe hydrotalcite composite catalyst was obtained.It is found that the active area of the catalyst can be changed by changing the electrochemical deposition time,the concentration of the deposition solution and the proportion of metal in the deposition solution during the preparation process,thus changing the catalytic activity of OER.The prepared AgNWs/CoFe hydrotalcite composites had good catalytic performance with 150 mV overpotential afford a current density of 10 mA/cm².Moreover,the obtained catalysts still had catalytic activity of 90%after 6 hours of stability test.