Controllable Preparation Of Platinum Group Metal(PGM)-based Catalyst And Its Application In The Field Of Hydrogen Energy

Hydrogen energy,which is considered to be the most environmentally friendly and sustainable clean energy,has received widespread attention.However,hydrogen energy involves complicated and slow chemical reactions such as hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and oxygen reduction reaction(ORR)in the energy conversion of hydrogen production by electrolysis of water and hydrogen used in fuel cells.Therefore,it is necessary to develop efficient and stable catalyst.Based on these,this article takes Ru,Ir,Pt and other platinum group metals(PGM)as the main active ingredients,a series of catalysts are prepared through the catalyst composition,morphology and structure design aiming at the above-mentioned different catalytic systems,and the reasons for their increased activity are analyzed in detail.The main research results are as follows:(1)In view of the Ru has a good hydro-precision ability,the carbon support ultrafine RuO2 catalyst having a typical strawberry structure is prepared by solid phase grinding and annealing at low temperature under air,and the average particle size of RuO2 is only 1.82 nm.The activation energy can only be 28.5 kJ mol-1 in the case of catalyzing hydrogenation of ammonia borane for hydrogen production.Further,in the case of alkaline water electrolysis for hydrogen production,it exhibits an ultra-low overpotential(only 8 mV)at 10 mA cm-2 current density,which is significantly better than the performance of commercial Pt/C.The density functional theory(DFT)calculation results show that the unique C-Ru-C chemical bond formed in interface of the composite catalyst is the main reason for the significant increase in hydrogen evolution activity.(2)Based on the good oxygen evolution activity and stability of Ir,The Ir/C composite catalyst with an average particle size of 3.68 nm was prepared using a high-temperature carbothermal solid-phase reduction method assisted by dopamine.It exhibite an overpotential of only 276 mV at a current density of 10 mA cm-2,and the mass activity is 0.185 A mgIr-1,which is 5.4 times of that of the commercial IrO2(0.034 A mgIr-1),and it shows a more excellent chemical stability than commercial catalysts.XPS result confirms the existence of a small amount of IrO2 on the Ir surface,forming a unique IrO2@Ir heterojunction structure,resulting in acceleration of OER dynamics process.(3)Taking the application of high-activity OER/ORR bifunctional oxygen electrode as the traction,a platinum alloy+metallic iridium/carbon composite catalyst with a typical phase separation structure was prepared using the glycol reduction method by controllable synthesis of PtCoW alloy nanocrystals on the surface of Ir/C working as the structure-oriented template.In the acid/alkaline environment,it exhibits excellent OER/ORR dual-function electrocatalytic performance.Among them,the ORR mass activity is 0.73 A mgpt-1,which is 5 times that of commercial Pt/C(0.14 A mgPt-1);the OER mass activity is 0.54 A mgIr-1,which is 10 times that of commercial IrO2(0.05 A mgIr-1).The theoretical calculation results of DFT analyzed the kinetic processes and control steps of the two reactions at the atomic level,and proposed that the electron transfer between the two active components was the main reason for the increase in activity.