Application Of Prussian Blue Analog Composite Catalysts In Electrocatalytic Water Splitting

Energy shortage and environmental pollution have become two major problems in the modern economy.The key to solving these two problems is to develop sustainable,renewable,low-carbon energy sources to replace traditional fossil fuels such as coal,oil,and natural gas.The most common green energy sources include solar energy,wind energy,hydro energy,etc.However,energy sources like solar energy and wind energy are intermittent,and they are difficult to produce and release when needed.Recently,hydrogen has received attention as one of the renewable and sustainable alternative energy sources.Electrochemical water splitting can produce high-purity hydrogen,so it has become the most potential hydrogen production technology.The water electrolysis process involves two half-reactions,namely the hydrogen evolution reaction（HER）at the cathode and the oxygen evolution reaction（OER）at the anode.In theory,only 1.23 V is needed to drive the water electrolysis reaction,but due to the slow kinetics of the OER process,the driving potential required to overcome the activation energy barrier between the two half-reactions under practical conditions is much higher than theoretical conditions,which reduces the efficiency of water splitting.Therefore,it is very necessary to find electrocatalysts with high activity,high stability and low cost to improve the efficiency of water splitting.Prussian blue analog materials have the characteristics of low price and easy synthesis,and have been used in electrochemical energy conversion related fields.In addition,among many transition metal electrocatalysts,metal selenides have the characteristics of excellent electrical conductivity and high volumetric energy density,exhibiting good electrocatalytic performance.Thus,metal selenides have become one of the hottest materials as good substitute for precious metal catalysts that have attracted attention in recent years.In this thesis,the prussian blue analog precursor was first synthesized by room temperature aging method,and then the precursor was selenized by hydrothermal method and vapor deposition method,to synthesize prussian blue selenide with good electrical conductivity.The above samples were studied in terms of phase,morphology,element composition and electrocatalytic oxygen evolution reaction performance.This thesis mainly includes the following contents:In the first part,the prussian blue analog precursor was first synthesized by the room temperature aging method,and then sodium hydroxide and selenium powder were placed in a reaction kettle,and the reaction was carried out at 220°C for 24 h.After the prussian blue analog precursor was lowered to room temperature it was transferred to the same reactor,and Fe-CoSe₂containing selenium impurities was synthesized at 220°C for 18 h,and then calcined in a tube furnace to remove selenium impurities to obtain Fe-CoSe₂.The phase and composition of the optimized samples were tested,and the prepared catalysts improved the shortcomings of the poor conductivity of the precursors,and had good electrocatalytic oxygen evolution performance.In the second part,a trimetallic prussian blue selenide was designed and synthesized by adding another metal on the basis of the bimetallic catalyst.Firstly,NiCoFePBA precursor was synthesized by room temperature aging method,and then NiCoFewas etched in ammonia solution at room temperature to obtain NiCoFecubecages,Then the etched samples were placed in a tube furnace at 350°C for 2 h to be selenized.The prepared catalysts were subjected to a series of the characterization.The NiCoFeSe cubecages have shown to have good electrochemical performance,and the catalyst also has excellent stability.