Synthesis and Electrochemical Properties of Two-Dimensional Hafnium Carbide.

The preparation of MXenes is mainly obtained by selective etching of Al atoms in MAX phase material with Al A position in HF acid, NH4HF2 solution, LiF and HCl mixture solution and low eutectic mixed salt medium. Since it is difficult for transition metals Zr and Hf to form MAX phase with A as Al, there is no report on MXenes materials of Zr and Hf series up to now. Compared with Zr series materials, Hf lamellar carbide is more difficult to obtain a single phase, the researchers based on the solution method of tuning unit cell in the thinking of the layer, the introduction of a small amount of Si at Al, using SPS method to synthesize a new type of solid material, in solid solution as the precursor, with Hf acid etching agent, realized with Al (Si) - C structural unit of selective discrimination, The Hf two-dimensional MXenes material was obtained for the first time. By means of binding energy and atomic charge calculation, the micromechanism of Si doping promoting hydrofluoric acid stripping process was elucidated. Hf series of novel two-dimensional carbide materials have potential applications in energy storage, wave absorption and optoelectronic devices. High volume specific capacity materials are expected to be used in miniaturized energy supply systems such as space vehicles and mobile equipment.