Preparation Of CoFePBA Derived Materials,CoFePBA-Based Composites And Study On Their Electrocatalytic Oxygen Evolution Reaction Performance

Water splitting is a promising way of clean hydrogen production and an energy conversion technology for renewable energy utilization.Oxygen evolution reaction（OER）is the key semireaction of electrolytic water.However,its slow oxygen evolution kinetics has become a major obstacle to hydrogen production from water splitting.In order to accelerate the reaction rate of OER reaction,reducing the overpotential（η）of the reaction and achieving higher oxygen production efficiency with the lowest energy consumption are extremely urgent to search electrocatalysts with high activity.In recent years,bimetallic catalysts represented by transition metal cobalt（Co）and iron（Fe）have become the research focus of high-performance OER electrocatalysts.Prussian blue analogues（PB As）are a kind of important coordination compound materials,which have a good application prospect in the field of electrocatalysis due to their special microstructure.Due to the high electrocatalytic activity of Co and Fe bimetals,CoFePBA has been widely used in OER catalyst.However,CoFePBAhas the disadvantages of poor electrical conductivity and weak stability,so it is necessary to find an appropriate way to effectively improve the performance of CoFePBA.In this paper,the electrocatalytic performance of CoFePBA was effectively improved by low temperature heat treatment,phosphating treatment,sulfuration treatment,and the formation of the composite of CoFePBA and one-dimensional nanomaterial.1.CoFePBA material was prepared via chemical deposition method,and it was heat-treated at different low temperatures.The influence of Co3+/Co2+ratio of the product under different heat treatment temperature on the electrocatalytic performance of OER was investigated.According to XPS calculation and FT-IR analysis,the CoFePBA-200,which was obtained after 2 h of heat treatment at 200℃ in N2 atmosphere,has the highest proportion of Co3+/Co2+.The electrochemical test results showed that CoFePBA-200 exhibited the best electrocatalytic performance,and showed a low overpotential of 312 mV at the current density of 10 mA cm-2 in 1.0 M KOH electrolyte.The derivative strategy of low temperature heat treatment exposes more Co3+while maintaining the original skeleton structure of CoFePBA,thus effectively improving the electrocatalytic activity of OER.2.CoFePBA material was prepared via chemical deposition method.Then,phosphating and sulfurization heat treatment were carried out at different temperatures,and the influence of different treatment temperatures on the OER electrocatalytic performance was explored.For phosphating treatment,nano-composite materials based on different phosphating materials can be formed.Due to the excellent catalytic performance of phosphide and the good synergistic catalytic effect between different phosphide phases,the product showed good electrocatalytic activity.For sulfurization treatment,the content of sulfide phase in the product is very low,and the main phase is still PBA.However,each component phase in the composite can form a good synergistic catalytic effect,the electrocatalytic activity of the product has been significantly improved.P-350 and S-350,which were obtained at a heat treatment temperature of 350℃,showed low overpotentials of 257 and 281 mV,respectively,at a current density of 10 mA cm-2 in 1.0 M KOH electrolyte.3.MnO2 nano wires were prepared via hydrothermal method.Then,CoFePBA nanocubes were grown on the surface of MnO2 nanowires via co-deposition.method to form MnO2@CoFePBA nanocomposites.The electrochemical performance of the composite is significantly better than that of CoFePBA and MnO2 nanowires due to the synergistic interaction between different components.When used MnO2@CoFePBA as OER electrocatalyst,the overpotential at 10 mA cm-2 in 1.0 M KOH is 384 mV,showing good electrocatalytic activity.