Exceptional Suppression of the Self-Discharge Behavior of Supercapacitors by Precisely Tuning the Surface Assets of MXene by a Spontaneous Single-Atom Doping Strategy

MXene-based supercapacitors (SCs) are widely regarded as promising energy storage devices. However, the inevitable and ignored self-discharge behavior of MXene-based SCs causes an unavoidable voltage decay and energy loss. Herein, the Ru single-atom doping strategy is used to fabricate a Ru-MXene film to modulate the surface properties of MXene, and the assembled Ru-MXene film-based SC showed a suppressed self-discharge behavior due to the simultaneously reduced activation-controlled and diffusion-controlled reactions. Regarding the self-discharge mechanism, three positive synergistic effects including increased adsorption energy, increased work function, and oxidation of the Ti atom of Ru-MXene simultaneously led to suppressing the self-discharge behavior. Benefiting from abundant electroactive sites and higher adsorption energy, the assembled Ru-MXene film-based SC exhibited an excellent electrochemical performance. This work provides a glimpse into the single-atom doping strategy to suppress the self-discharge behavior of MXene-based SCs and a prospective guide to promote their practical applications.