Preparation And Electrocatalytic Properties Of Noble Metal-Supported Two-dimensional Transition Metal Compound MXene Catalysts

Hydrogen energy has become a clean energy in the future because of its environmental protection and renewability.Hydrogen production from water splitting is considered as a solution for hydrogen energy conversion and storage.In recent years,low-cost non-noble metal materials have been widely studied,but they exhibit lower activity and stability than supported noble metal catalysts,especially noble metal platinum catalysts,and cannot achieve large-scale applications.However,supported noble metal catalysts have the problems of high cost,easy agglomeration of nanoclusters or particles,and the loss of catalytic activity due to the blocking of active sites with high surface free energy.Therefore,designing a facile preparation method to develop efficient and highly active supported noble metal catalysts has a positive impact.The two-dimensional layered transition metal compound MXene has become a popular support material due to its excellent electronic conductivity,bulk capacitance,and chemical stability.Taking full advantage of its structure and performance,exposing more active sites and increasing specific surface area through physical and chemical means,the controllable loading of metal clusters on supports has become the research frontier in the current field of catalysis.The formation of composite noble metal nanostructures by MXene and metal can make noble metals well dispersed,form a metal-support interface with high thermal stability,accelerate the electron transfer between the support and metal nanoclusters,and obtain low loading,excellent electrochemical HER activity and stability.It can provide effective methods for future energy storage,energy conversion,and hydrogen energy industrialization.In this study,we investigated a mechanochemical ball-milling method for the formation of platinum nanoclusters,which are fixed on twodimensional transition metal carbides MXene(Ti2CTx and Nb2CTx).After high-temperature heat treatment,nanoclusters are formed on the supported catalysts as enhancement catalysts for hydrogen evolution.Compared with other HER catalysts and commercial Pt/C catalysts,the prepared target catalyst exhibits excellent electrochemical HER activity and stability.For Pt/Ti2CTx-900,the overpotential is only 1.7 mV at 10 mA cm-2(Ej10)41 mV at 100 mA cm-2(Ej100).The Pt/Nb2CTx-600 catalyst demonstrates superior electrochemical HER activity with an ultralow overpotential of 5 mV and 46 mV to achieve 10 mA cm-2 and 100 mA cm-2.In addition,accelerated durability testing(ADT)and long-term chronocurrent testing(CA)also confirmed superior durability.The excellent HER performance is attributed to high Pt dispersion and more active sites exposed by mechanochemical processes and heat treatment.As a result,this easy-tooperate strategy has enabled HER to develop an excellent low-cost electrocatalyst,paving the way for the future development of other highly active and robust functional composites.