Thickness‐Independent Capacitive Performance of Holey Ti3C2Tx Film Prepared through a Mild Oxidation Strategy

Abstract

The Ti3 C2 Tx film with metallic conductivity and high pseudo-capacitance holds profound promise in flexible high-rate supercapacitors. However, the restacking of Ti3 C2 Tx sheets hinders ion access to thick film electrodes. Herein, a mild yet green route has been developed to partially oxidize Ti3 C2 Tx to TiO2 /Ti3 C2 Tx by introducing O2 molecules during refluxing the Ti3 C2 Tx suspension. The subsequent etching away of these TiO2 nanoparticles by HF leaves behind numerous in-plane nanopores on the Ti3 C2 Tx sheets. Electrochemical impedance spectroscopyshows that longer oxidation time of 40min yields holey Ti3 C2 Tx (H-Ti3 C2 Tx ) with a much shorter relax time constant of 0.85s at electrode thickness of 25 µm, which is 89times smaller than that of the pristineTi3 C2 Tx film (75.58s). Meanwhile, H-Ti3 C2 Tx film with 25min oxidation exhibits less-dependent capacitive performance in film thickness range of 10-84 µm (1.63-6.41mgcm-2 ) and maintains around 60% capacitance as the current density increases from 1to 50Ag-1 . The findings clearly demonstrate that in-plane nanopores not only provide more electrochemically active sites, but also offer numerous pathways for rapid ion impregnation across the thick Ti3 C2 Tx film. The method reported herein would pave way for fabricating porous MXene materials toward high-rate flexible supercapacitor applications.