Surface-Engineered Mo2TiC2Tx MXene for Moisture-Resilient High-Performance Energy Storage

Abstract

Two-dimensional MXenes are promising electrode materials for electrochemical energy storage; however, their practical deployment is limited by moisture-induced degradation arising from hydrophilic surface terminations. Here, we report a low-energy ionbeam engineering strategy that converts intrinsically hydrophilic Mo2TiC2Tx MXene into a moisture-repellent and structurally stable material while preserving its layered architecture.Selective modification of surface terminations yields a robust water contact angle of about 130°, effectively suppressing moisture adsorption and mitigating environmental degradation without inducing structural damage. The ion-beam-treated MXene exhibits nearly a twofold increase in specific capacitance (187 Fg -1 at 1 Ag -1 ) and improved cycling stability, retaining 86% of its capacity after 2000 cycles, compared with pristine MXene. The improved electrochemical performance originates from irradiation-induced defect formation and electronic structure modulation, which enhance charge transport and pseudocapacitive behaviour. Density functional theory calculations support these findings by revealing reduced adsorption of polar species and an increased density of states near the Fermi level, indicative of enhanced electrical conductivity and quantum capacitance. This work establishes ion-beam surface engineering as an effective route to stabilize MXenes against moisture-driven degradation while concurrently improving their electrochemical robustness.