Preparation And Performance Research Of Electrocatalytic Material For Anodic Oxygen Evolution Reaction In Acidic Water Electrolysis

With the consumption of fossil resources and the increasing demand for energy in the world,the energy crisis and environmental problems have become more and more serious.Therefore,the development of"green,clean,and low-carbon"new energy has become a general trend.As a clean secondary energy carrier,hydrogen energy has the advantages of high calorific value,non-polluting products,and can be transported,which has attracted widespread attention from countries all over the world.Proton exchange membrane（PEM）electrolyzed water can utilize non-grid-connected renewable energy such as solar energy and wind energy.It can efficiently produce high-purity hydrogen under high current density and is considered to be one of the most promising green hydrogen production technologies.However,this technology can only operate in acidic environment,and only a few precious metals can achieve acidic water splitting under electrode polarization conditions.The resulting high energy consumption and high cost have become a bottleneck restricting the development of acidic electrolyzed water.The resulting high energy consumption and high cost have become a bottleneck restricting the development of acidic electrolyzed water.Therefore,the development of high-efficiency,low-cost,acid-stable electrocatalytic materials has become a key issue for the large-scale application of PEM water electrolysis technology.Ru belongs to the Pt group noble metal elements.In electrolyzed water,Ru-based materials have broad application prospects due to their outstanding catalytic performance,suitable for different pH and the cheapest price among noble metals.However,Ru-based materials have serious stability problems,especially in the anode oxygen evolution reaction process,RuO₂ is very unstable under high voltage,and it is easily oxidized to RuO₄ and dissolved,which seriously affects its practicality.Therefore,this article adopts a variety of strategies to control Ru-based catalysts,and electrocatalytic materials with high activity and high stability in acidic environment were obtained.The relationship between composition,structure and electrocatalytic performance was deeply studied,and the reaction mechanism was revealed.The specific contents are as follows:（1）La-doped RuO₂ catalysts were prepared by hydrothermal and annealing methods.It showed high-efficiency and long-lasting electrocatalytic performance for both OER and HER in acidic environment.Through electrochemical tests,it is found that the electrochemical performance of La-doped RuO₂ catalyst increases first and then decreases with the increase of temperature.At the annealing temperature of 400℃,La-doped RuO₂ showed the best catalytic performance.The overpotential required to reach 10 m A/cm² was only 208 mV and 71 mV for OER and HER,respectively.By using La-doped RuO₂ as anodic and cathodic catalysts for water splitting in 0.5 M H₂SO₄,a cell voltage of only 1.53 V was needed to provide 10 m A/cm²with excellent long-term durability over 24 h.Through a series of structural characterization,it was found that the doping of La increased the concentration of oxygen vacancies in RuO₂ and reduced the particle size of RuO₂.DFT calculations and experimental observations showed that the doping of La to RuO₂ effectively adjusts the d-band structure of Ru centers,reduces the adsorption energy of substances and promotes the desorption of substances on the surface of La-doped RuO₂.Therefore,the electrocatalytic activity and stability of RuO₂ were improved.（2）The RuO₂ evenly loaded on C₃N₄ was prepared by sol-gel method and annealing method.Because of the large specific surface area of C₃N₄ and the excellent electrical conductivity of carbon materials,the atom utilization rate of RuO₂ was improved,and more active sites were exposed,which improved the electrocatalytic activity of RuO₂ and reduced the amount of RuO₂.It can be used as an excellent bifunctional electrocatalyst.The overpotential required to reach 10 m A/cm² was only 240 mV and 109 mV for OER and HER,respectively.The potential of overall water splitting was 1.6 V,and it can maintain stability for24 h in 0.5M H₂SO₄ solution,which was better than commercial RuO₂and commercial Ir O₂catalytic materials.