Preparation Of Pd And Au Based Precious Metal Catalysts And Their Catalytic Performance For The Electrooxidation Of NaBH₄

Direct sodium borohydride fuel cell?DBFC?is an efficient clean power plant that converts the chemical energy stored in sodium borohydride directly into electric energy.DBFC has been widely concerned in the world due to its high theoretical open circuit voltage with high power density,facile to store and transport solid fuel,no CO poisoning and other advantages.However,there are still some issues to be solved in order to achieve its commercial application.Therefore,the main development direction for DBFC are developing the anodic catalysts with high activity,various selectivity,low cost and suitable structure to improve the electro-oxidation performance of sodium borohydride.In response to the above problems,this paper mainly studies the three-dimensional nanowire array electrode loaded with precious metals Pd,Au and its catalytic performance for the electro-oxidation of NaBH₄.The main contents are as follows:Ni nanowire array electrodes with three-dimensional open structure are obtained by template-assisted electrodeposition.Then,noble metal Au is deposited on the three-dimensional Ni nanowire array electrode by galvanostatic electrodeposition method to obtain three-dimensional Au@Ni nanowires.In addition,Pd is grown on three-dimensional Ni nanowire array electrode by an in-situ growth method to achieve a three-dimensional Pd@Ni nanowire array electrode supporting precious metal Pd.The structure and morphology of this electrode are characterized by SEM and TEM.The composition of electrode is analyzed by XRD and ICP.The oxidation current density of three-dimensional Au@Ni nanowire array electrode is as high as 126 mA/cm² at-0.5 V?vs.Ag/AgCl?in the concentration of 2.00 M NaOH with 0.24 M NaBH₄ solution under the three-electrode test system.Simultaneously,the oxidation current density of three-dimensional Pd@Ni nanowire array electrode at-0.5 V?vs.Ag/AgCl?is as high as 209 mA/cm² in 1.00 M NaOH with 0.12 M NaBH₄ solution.C@TiC nanowire array electrodes are prepared by chemical vapor deposition.Then Ni/C@TiC,Au₁Ni₄/C@TiC,Au₁Ni₂/C@TiC,Au₂Ni₁/C@TiC,Au₄Ni₁/C@TiC,Au/C@TiC nanowire array electrodes with different alloy contents are manufactured by changing the concentration ratio of gold and nickel in the electrolyte.The structure and morphology of obtained electrode are characterized by SEM and TEM.The XRD and ICP are utilized to analyze the composition of the electrode.The results show that the Au-Ni/C@TiC electrode owns a dendritic structure.And the three-dimensional Au1Ni1/C@TiC nanowire array electrode demonstrates the best catalytic performance towards NaBH4 electro-oxidation.The oxidation current density of Au₁Ni₁/C@TiC nanowire array electrode is 102 mA/cm² at-0.5 V?vs.Ag/AgCl?under the three-electrode test system in 2.00 M NaOH with 0.20 M NaBH4 solutions.Lastly,DBFC is assembled by utilizing Au1Ni1/C@TiC nanowire array as anode and Au/C deposited of gold on carbon cloth as cathode,which investigates the effects of concentration,flow rate and temperature on the performance of this full battery.