Synthesis And Electrocatalytic Performances Of Ti₃C₂T_x Mxene Matrix Composites

In recent years,due to energy shortages and environmental pollution,the development of clean and sustainable energy has become more and more popular.Efficient catalysts for the development of hydrogen evolution reactions（HER）and oxygen evolution reactions（OER）in water electrolysis cell plants and oxygen reduction reactions（ORR）in metal air cells have become the focus.In this paper,three Ti₃C₂T_xMXene matrix composites were prepared by different methods,and the structure and surface morphology were determined by a series of characterization methods.As an electrocatalyst,the electrocatalytic properties of HER,OER and ORR were studied.The details are as follows:（1）A novel electrocatalyst based on an exfoliated two-dimensional（2D）MXene（Ti₃C₂T_x）loaded with bimetallic oxide nanoparticles（NPs）of Pt and Pd（represented by PtO_aPdO_bNPs@Ti₃C₂T_x）,which was synthesized via solution plasma（SP）modification.The electrochemical test results show that PtO_aPdO_bNPs@Ti₃C₂T_x has excellent HER and OER properties,with a low onset potentials and Tafer slopes.Moreover,water electrolysis using this catalyst achieved a water splitting current density of 10 mA cm^-2 at a low cell voltage of 1.53V in 1.0 M KOH solution.（2）A facile synthesis of Co species（i.e.,metallic Co and Co oxide）combined with CNTs and loaded onto the graphene-like titanium carbide（CoO_x-N-C@TiO₂C）,which were derived from the hybridization of CoZn-ZIF and Ti₃C₂T_x MXene（CoZn-ZIF@Ti₃C₂T_x）composite through an interdiffusion reaction strategy.The obtained CoO_x-N-C@TiO₂C composites showed remarkable electrocatalytic activities toward the three reactions of ORR,OER,and HER.the CoO_x-N-C@TiO₂Ccatalyst achieved a water-splitting current density of10 mA cm^-2 at a low cell voltage of 1.45 V,and the overall oxygen electroactivity on CoO_x-N-C@TiO₂C as appraised byΔE(=E_{j（OER）=10}-E_1/2（ORR）)was 0.72 V.（3）A new type of electrocatalyst MCA@Ti₃C₂T_x was obtained by in-situ reaction of Ti₃C₂T_x MXene nanosheets and cyanuric acid-melamine supermer（MCA）,and further calcined at different temperatures（500,700,950°C）.TiO₂C@CNx nanosheets showed that the TiO₂C@CNx nanosheets(TiO₂C@CN_x,950)calcined at 950°C exhibited strong and efficient multifunctional electrocatalytic activity for HER,OER and ORR.the TiO₂C@CN_x,950 catalyst gives a water-splitting current density of 10 mA cm^-2 was achieved at a low cell voltage of 1.50 V.And the overall oxygen activity was only 0.75 V.In view of its excellent OER and ORR performance,we applied it to the zinc-air battery.The open circuit voltage is 1.344 V and the power density is 91.8 mW cm^-2.This paper further expands the application range of Ti₃C₂T_x MXene in the field of electrocatalysis,and broadens the road for the development of efficient and stable electrocatalysts.