Low-cost Fabrication Of Cobalt-iron-boron Nanosheets For Electrochemical Properties

Along with the rapid development of China's economy,energy shortages and environmental crises have become increasingly serious,and there is an urgent need to develop new energy materials to meet energy and environmental requirements.In the current research hotspots,supercapacitors and electrolyzed water are two key research directions.However,the performance and interpretation of existing electrode materials are not perfect,and it is urgent to develop a new electrode material to meet the needs of the application.Recently,compounds formed by metals and non-metals have attracted the attention of many researchers,among which boride has received a lot of attention due to its unique structure and excellent physical and chemical properties.In this paper,the acid-treated nickel foam was used as the matrix,and the amorphous cobalt-iron boride was supported on the surface by chemical reduction.The composite electrode of self-supporting nano-sheet Co-Fe-B and nickel foam was prepared.And we studied its supercapacitance characteristics and electrolyzed water properties.In the first part of the thesis,a method for preparing a large amount of transition metal boride on a nickel foam substrate was proposed,and a cobalt iron boride electrode material was prepared.By optimizing the ratio of cobalt to iron,controlling the reaction time and the concentration of the reaction product,the structure and performance of electrode material was optimized.The morphology,structure and composition of the prepared boride were analyzed by SEM,TEM and XPS.By electrochemical performance test,the specific capacitance of the electrode material exhibits high as1073 F g^-1,and the assembled asymmetric supercapacitor holds 126%of the original performance tested in the cycle stability.The performance is further explained in the paper,and the reasons for the excellent performance are summarized in many aspects.It is revealed that the proper ratio of cobalt to iron provides the best synergistic effect of cobalt and iron,making full use of the advantages of both.It has been investigated that the amorphous structure due to the disordered atomic arrangement has the property of improving electrochemical performance.Experiments have shown that the advantage of cobalt iron borides relative to cobalt iron oxides is an increase in electrical conductivity.It has been summarized that the excellent electrical conductivity of the nickel foam matrix leads to rapid ion migration and electron transportation.In the second part of the thesis,the performance of cobalt-based catalysts was improved by utilizing the performance advantages of cobalt-based catalysts and the introduction of iron.The cobalt and iron borides prepared in the first part were tested for HER and OER properties.The results show that the prepared boride has both high OER and HER catalytic activity.Subsequently,the boride was assembled into a two-electrode electrolyzed water apparatus,resulting in a lower electrolysis water overpotential and good long-term cycle stability.