Preparation Of Titanium-oxide Supported Iridium Catalyst And Its Catalytic Performance For PEM Electrolytic Water Reaction

Proton exchange membrane electrolysis for hydrogen production from water is widely used due to its excellent performance,but its large-scale application is limited due to its high anode catalyst（Ir）.This paper aims to reduce the amount of precious metal used in anode Ir to reduce the overall cost.Titanium oxide is a stable,easy to obtain,cheap support,using titanium oxide as the carrier of oxygen evolution catalyst,can effectively improve the catalytic activity of Ir,so as to reduce the amount of Ir in the membrane electrode assembly（MEA）.Therefore,it is of practical significance to study the preparation and characterization of titanium-oxide-supported iridium catalysts in proton exchange membrane electrolysis in water.The main contents of this paper are as follows:（1）Oxygen evolution catalyst Ir/TiO₂was prepared by polyol method,and homogeneous nanoparticles with particle size less than 3.5 nm were obtained.The support and oxygen evolution catalyst were analyzed and tested by characterization methods,and suitable support was screened.By changing the amount of catalyst in the membrane electrode assembly（MEA）and analyzing the voltage loss through single cell test,the internal relationship between the voltage loss and the amount of catalyst was revealed,and the best cell performance was obtained at 0.204-0.304 mg _Ir/cm².（2）In order to improve the conductivity of oxygen evolution process,using electrochemical impedance spectrum（EIS）analysis technology,this paper proposes to add Warburg diffusion element to the equivalent circuit diagram to analyze the mass transfer diffusion process at low frequencies.The analysis of oxygen evolution process and single electrolytic cell shows that the thickness of catalytic layer should be kept within a certain range,otherwise the mass transfer diffusion impedance will increase significantly.At the same time,due to the poor conductivity of titanium oxide,this paper uses high temperature reduction method to load Pt into titanium fiber mat to enhance the overall conductivity of electrolytic cell.The performance of single electrolytic cell is 2.04 V@1 A/cm²at 60℃.（3）IrO₂/Ti₄O₇nanoparticles with Ir content of 53%were prepared by molten salt method.The surface morphology of IrO₂/Ti₄O₇nanoparticles was adjusted by potassium hydroxide（KOH）,and the precursor solution was adjusted by citric acid（CA）to form a complex to promote uniform dispersion.It can ensure that the particle size of nanoparticles is kept at about 5 nm,and effectively control the particle size of nanoparticles.Thus,the electrochemical performance is 300 m V@10 m A/cm²,and the electrolytic cell performance is1.7912 V@1 A/cm²at 80℃.