Titanium-vacancy-based Ti3C2Tx MXene with In-Situ Loaded ultra-low platinum demonstrating outstanding hydrogen evolution performance in acidic seawater

MXenes have emerged as promising support materials for Pt nanoparticles due to their large surface area and exceptional conductivity, which can substantially reduce Pt loading while enhancing hydrogen evolution reaction (HER) activity per unit mass of Pt. Consequently, structural optimization of MXenes to simultaneously improve Pt atomic utilization efficiency and interfacial stability has become a critical research focus. This study presents a novel strategy utilizing Ti 3 C 2 T x MXene with engineered Ti vacancies as a support for synthesizing Pt@MXene (PMX- x ) electrocatalysts through a self-reduction stabilization process. Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) analyses reveal the presence of Ti vacancies in the MXenes structure at varying concentrations, which are significantly reduced or eliminated upon Pt incorporation, accompanied by strong interactions between Pt and MXenes. Density functional theory (DFT) calculations demonstrated that Pt atoms occupied Ti vacancy sites and achieved optimal hydrogen adsorption free energy (ΔG H* = -0.38 eV), and finally leading to a significantly improved HER kinetics. As a result, the optimized catalyst exhibited superior electrochemical performance in 0.5 M H 2 SO 4 , which was 16.8-fold in Pt mass activity (5.05 A mg·Pt −1 at η = -75 mV) compared to commercial Pt/C (0.30 A mg·Pt −1 at η = -75 mV). This vacancy-mediated anchoring strategy establishes a new paradigm for designing high-efficiency, low-Pt electrocatalysts and demonstrates promising potential for industrial applications.