Flexible and freestanding Mo2CTx film electrode with high capacitive properties in aqueous electrolytes

Two-dimensional nanolayered Mo 2 CT x is an excellent electrode material due to its large surface area and high conductivity. In this paper, Mo 2 C powders and metal Ga with the molar ratio of 1:3 as raw materials were used to prepare phase-pure Mo 2 Ga 2 C ceramic materials by non-pressure sintering at 750 °C, and two-dimensional nano-layered Mo 2 CT x materials were etched successfully using a facile oil bath method by HF. Capacitive behaviors of flexible and freestanding Mo 2 CT x film electrode prepared by the facile vacuum filtration in 1 M H 2 SO 4 , 1 M Na 2 SO 4 and 1 M NaOH electrolytes were systematically investigated for the first time. Mo 2 CT x film electrode exhibits the pseudo-capacitive behavior in H 2 SO 4 electrolyte, while double layer capacitance is presented in Na 2 SO 4 and NaOH electrolytes. The maximum volumetric specific capacitance of 563.05 F/cm 3 at 2 mV/s is in H 2 SO 4 electrolyte, corresponding to the mass specific capacitance of 154.26 F/g. This is due to the obvious redox reaction in sulfuric acid solution Notably, density functional theory (DFT) calculation was executed to investigate the capacitive behavior and mechanism of the Mo 2 CT x film electrode in the three different electrolytes.