Fluorine-Free Preparation Of Two-Dimensional Ti₃C₂Tx MXene And Preparation Of Composites Of Two-Dimensional Material-Based Co₃O₄ And Oxygen Precipitation Catalytic Performance Study

Transition metal cobalt oxides（Co₃O₄）have been widely investigated as OER catalysts owing to high oxygen content ratio and easy loss of lattice oxygen.However,its characteristic of tending to agglomerate,which hinders the charge transfer during the reaction,leads to its unsatisfactory OER catalytic performance.Ti₃C₂Tx MXene is a class of two-dimensional layered materials with good hydrophilicity due to the abundant surface terminal groups,and the layered structure provides a large surface area,which allows Ti₃C₂Tx MXene to be used as a catalyst material substrate to load Ti₃C₂Tx MXene can be prepared by a variety of etching routes,and the Ti₃C₂Tx MXene prepared by different etching routes differ greatly in terms of surface ter terminal groups,size and flexibility.Previous studies have shown that Ti₃C₂Tx MXene with fluorine terminal group has poor stability in deionized water and air and is easily oxidized to Ti O₂.The mechanism of Ti₃C₂Tx MXene and g-C₃N₄ to improve the OER catalytic performance of Co₃O₄ was also investigated,and the specific findings are as follows:1、The fluorine-free Ti₃C₂Tx MXene was successfully prepared by etching the MAX-phase precursor Ti₃Al C₂ with saturated Na₂CO₃ solution using a mixture of DMSO and DMF,and the reaction time and temperature were continuously adjusted to determine the most suitable reaction temperature and time for the etching reaction,and finally the fluorine-free Ti₃C₂Tx MXene was successfully prepared by continuous stirring for 6 days at 80°C.The crystal structure and morphological structure information of Ti₃C₂Tx MXene were analyzed by XRD,SEM and TEM.2、In this paper,we designed a composite catalyst that uses layered g-C₃N₄ nanosheets as the carrier to support Co₃O₄ nanoparticles.The composite exposed effectively reduces the characteristics of Co₃O₄ agglomeration,and the synergy between solid phases improved the charge transfer rate,thereby improving the OER catalytic performance.The OER catalytic performance of the material was tested in a standard three-electrode system using 1M KOH solution as the electrolyte.The results showed that among all the prepared catalysts,Co₃O₄@g-C₃N₄ The composite catalyst exhibits an oxygen evolution overpotential of 340 m V,a Tafel slope of 120.92 m V·dec^-1,and a double-layer capacitance（Cdl）of 2.01 m F·cm^-2 when generating a current density of 10 m A·cm^-2.Compared with Co₃O₄ and g-C₃N₄ catalysts,Co₃O₄@g-C₃N₄ The OER catalytic performance of composite material catalysts has significantly improved.3、Two dimensional layered Ti₃C₂Tx MXene was prepared using the optimized Li F/HCl etching method.The crystal structure and chemical composition information of the samples were analyzed through XRD,and the morphology and structure of the prepared samples were characterized using field emission SEM and TEM.The surface element composition and valence distribution of the samples were characterized and analyzed using XPS.The OER catalytic performance of the prepared material was tested in 1M KOH,and the results showed that using layered Ti₃C₂Tx MXene as the catalyst carrier significantly improved the OER catalytic performance of the catalyst.At a current density of 10 m A·cm^-2,Ti₃C₂Tx/Co₃O₄@g-C₃N₄ The required overpotential is 247 m V,which is much lower than pure Ti₃C₂Tx MXene （664 m V）,Ti₃C₂Tx/Co₃O₄（365 m V）,and Ti₃C₂Tx/g-C₃N₄（449 m V）.