Preparation And Electrocatalytic Hydrogen Evolution Reaction Performance Of MXene/Pt Composites

Water splitting to produce hydrogen is one of the effective ways to solve the current energy crisis.To date,platinum（Pt）is the best material for hydrogen production from water splitting.However,the shortage of metal Pt resources and high cost seriously limit its wide application.At present,the improvement of Pt-based materials mainly focuses on reducing the Pt usage and improving the utilization of Pt.In the study of Pt-based materials,two-dimensional（2D）materials are often used as carriers to improve the catalytic performance of Pt-based materials due to their large surface area and good conductivity.In this paper,thin layered Ti₃C₂T_x MXene was firstly synthesized,which was used as support for Pt-based materials.MXene/Pt-x and MXene/Pt_xNi_1-xnanomaterials were obtained and applied to the study of electrocatalytic hydrogen evolution performance.The main contents of this paper are as follows.1.First,thin layered Ti₃C₂T_x MXene was synthesized by using Li F/HCl as etchant to etch Al layer from Ti₃Al C₂ MAX,followed by ultrasonic dispersion stripping process.Then,the as-prepared thin layer MXene was used as support,on which Pt nanoparticles（NPs）with coral-like structure were loaded by ascorbic acid reduction method.A series of MXene/Pt-x nanomaterials were prepared by adjusting the amount of Pt precursor,and applied to electrocatalytic hydrogen evolution in acidic environment.Among them,MXene/Pt-3 nanomaterial showed the best catalytic performance for hydrogen evolution with overpotential of 302 m V@10 m A cm^-2 and Tafel slope of 79 m V dec^-1 and the coral-like structure remained intact after the stability test.From the TEM imges of MXene/Pt-3 nanomaterial with different reaction time,we analyzed the growth process of coral-like Pt NPs.XPS results showed that there was interaction between the support MXene and Pt NPs,which could promote the hydrogen evolution performance.The experimental results showed that not only the Pt-loading amount on MXene surface,but also the size of Pt NPs affected the catalytic performance.2.The composite of hollow Pt Ni NPs and MXene support was prepared by Na BH₄reduction method,and applied to the study of efficient catalytic hydrogen evolution performance.By optimizing the Pt/Ni ratio in the reaction system,the MXene/Pt_0.25Ni_0.75nanomaterial with the best catalytic performance was obtained.In 0.5 M H₂SO₄ electrolyte,the current mass activity of MXene/Pt_0.25Ni_0.75 nanomaterial was 0.40 A mg_Pt^-1@150 m V vs RHE,TOF value was 0.41 s^-1 and Tafel slope was 61 m V dec^-1.The catalytic performance of MXene/Pt_0.25Ni_0.75 nanomaterial was not only better than those of other Pt/Ni composites,but also better than those of MXene/Pt,Pt_0.25Ni_0.75 and Pt-black.We also explored the growth process of hollow Pt Ni NPs by TEM measurement of MXene/Pt_0.25Ni_0.75 samples with different reaction time.