In situ oxidized MoCT MXene film via electrochemical activation for smart electrochromic supercapacitors.

MoCT MXenes have great potential for multifunctional energy storage applications because of their outstanding electrical conductivity, superior cycling stability, and high optical transmittance. In this study, we fabricate MoCT film electrodes (referred to as MoC) on fluorine-doped tin oxide (FTO) substrates using the layer-by-layer (LbL) self-assembly technique. To improve the energy-storage performance of MoCT film electrodes, we develop a convenient electrochemical activation process to prepare in situ oxidized MoCT/MoO film electrodes (referred to as EA-MoC). The MoCT/MoO hybrid film benefits from the addition of MoO, which introduces extra redox sites and enhances the charge-storage capacity. Furthermore, the unique layered structure of MoCT significantly reduces the diffusion energy barrier for cations. The synergistic interaction between MoCT and MoO results in superior electrochemical performance, and the EA-MoC displays a remarkable increase in areal specific capacitance, achieving 23.29 mF cm at a current density of 1.5 mA cm, which is 518 % higher than that of MoC. The electrochromic supercapacitor, assembled using EA-MoC as the ion-storage layer and polyaniline (PANI) as the electrochromic layer, enables power visualization and quantitative display. In summary, this study utilizes in situ electrochemical activation to derive high-performance electrode materials, offering an innovative strategy for advancing MXene-based energy-storage materials.