Preparation And Performance Of Efficient Anode Catalysts For Direct Borohydride Fuel Cell

Due to the advantages of high theoretical open-circuit voltage,high specific capacity,high conversion rate,convenient fuel transportation,and safe storage,direct borohydride fuel cells?DBFC?have attracted much attention.Although in theory,the electrochemical oxidation of BH₄^-is an eight-electron reaction.In fact,the number of electrons released by electrochemical oxidation of BH₄^-depends on the performance of the anode catalyst.DBFC's high-efficiency anode catalyst not only requires high activity,but also inhibits the hydrolysis of BH₄^-.The use of non-precious Ni as the anode catalyst for DBFC has the advantages of low catalytic potential,low polarization,and low cost.Therefore,Ni-based catalysts were prepared by electroless plating,electrodeposition and electroless deposition?electrodeposition followed by electroless plating?on the basis of Ni,a non-precious metal,and their effects on the performance of Ni-based catalysts were studied.Firstly,different Ni-based catalysts were prepared by electroless plating,electrodeposition and composite methods.The results of SEM and XRD studies showed that the preparation methods significantly affected the morphology of Ni-based catalysts.Among them,the Ni-based catalyst prepared by the composite method has the largest specific surface area,which is favorable for increasing the contact surface between the catalyst and BH₄^-,increasing the catalytic active bit,and increasing the BH₄^-electrochemical oxidation performance.Electrochemical study found that under the action of Ni-based catalysts prepared by the composite method,the oxidation peak current density of BH₄^-can be as high as71.5 mA/cm².Under the nickel plating catalyst?9.4 mA/cm²?,the increase was 7.6times;under the effect of electrodeposited nickel,it was increased by 1.5 times?48.5mA/cm²?.And its discharge efficiency can reach 74%,which is 6.8 times?11%?under the action of electroless nickel plating catalyst and 3.2 times?23%?under electrodeposition nickel.The study also showed that the electrochemical oxidation reaction of BH₄^-was the least under the effect of the Ni-based catalyst prepared by the composite method.Obviously,the Ni-based catalyst prepared by the composite method significantly improves the electrochemical oxidation performance of BH₄^-,which lays an experimental foundation for greatly improving the performance of DBFC.In addition,the paper also explores the effect of rare earth La on the performance of electrodeposited Ni-based catalysts.The results show that the performance of the deposited Ni-based catalyst increases first and then decreases with the addition of LaCl₃,and the optimal concentration is 0.6 g/L.The electrochemical oxidation current density of BH₄^-can reach 113 mA/cm² under the action of deposited Ni-based catalyst prepared by addition of appropriate amount of LaCl₃,which is more than double that of the catalyst without La catalyst.The discharge efficiency was 41%,which was 11%higher than that without La addition.And the impedance of the BH₄^-electrochemical oxidation reaction is the smallest.