Zif-8-derived Porous Carbon-supported Au Nanocomposite Catalyst For Borohydride Electrocatalytic Oxidation

Direct borohydride fuel cell（DBFC）as a new green energy technology with very broad development prospects.It has the advantages of high open circuit potential,low operating temperature,high power density and no CO poisoning.The electrical oxidation（BOR）of borohydride in DBFC is an important reaction occurring at the anode,so the anode catalyst is one of the main factors affecting the overall performance and cost of DBFC.The DBFC anode catalyst usually uses more expensive precious metals,which increases its cost greatly,thus much more difficult to commercialize.Therefore,it is crucial to improve catalyst performance,reduce catalyst cost and improve fuel utilization.Meanwhile,the performance of anode catalysts is closely related to the structural properties of catalyst carrier materials.Therefore,finding a suitable catalyst carrier is an effective way to improve the performance of anode catalysts.In this thesis,different nitrogen-doped nanoporous carbon materials were prepared by ZIF-8 and its derivatives as precursors,and they were used as carriers to load Au catalysts,and their catalytic activities for BOR were investigated.The research for this paper is as follows:（1）Nitrogen-doped nanoporous carbon（NPC）was successfully prepared by a simple carbonization reaction under Ar atmosphere using ZIF-8 as the precursor,whose ligand is rich in nitrogen,so it is a good nitrogen source itself,and Au nanoparticles were successfully loaded onto NPC by impregnation reduction to obtain Au/NPC anode catalyst.The synthesized Au/NPC composite catalysts were physically characterized by TEM,XRD,and XPS.Their catalytic performance as DBFC anode catalysts for BOR was investigated using Au/NPC as a catalyst for BH4-electrooxidation.The Au/NPC catalyst was found to have higher catalytic activity for BOR than Au/C.（2）Fe-doped Fe-ZIF8 was synthesized by ultrasonically induced self-assembly,and simple carbonisation under Ar atmosphere was used to obtain Fe-NPC,a porous carbon material co-doped with iron and nitrogen.Au/Fe NPC catalysts were produced by impregnation reduction method,and the synthesized Au/Fe NPC composite catalysts were physically characterized by TEM,XRD,and XPS.The catalytic performance of the synthesized Au/Fe NPC composite catalyst was investigated as an anode catalyst for BOR.Among them,the Au/Fe NPC-40 catalyst possessed the highest catalytic activity.The corresponding peak current density is as high as 45.4m A cm^-2 and the number of transferred electrons is as high as 7.0.（3）Co-doped Co-ZIF8 was synthesized by ultrasonically induced self-assembly,and simple carbonisation under Ar atmosphere was used to obtain the cobalt-nitrogen co-doped porous carbon material Co NPC.Au/Co NPC catalysts were prepared by impregnation reduction method,and the structure and chemical composition of the synthesized Au/Co NPC composite catalysts were investigated by TEM,XRD,and XPS.It was used as an anode catalyst and its catalytic performance for BOR was investigated.The Au/Co NPC-40 catalyst was found to possess the highest catalytic activity.The corresponding peak current density is as high as 48.4 m A cm^-2 and the number of transferred electrons is as high as 7.5.