Defect-driven self-reduction of Pt on MXene for highly efficient hydrogen evolution

A defect-driven self-reduction strategy is proposed to exploit intrinsic Ti vacancies in Ti 3- x C 2 T 2 MXene to induce spontaneous reduction and atomic stabilization of Pt without external reducing agents. • The resulting Pt/Ti 3- x C 2 T 2 HD catalyst exhibits excellent acidic HER performance. • Pt/Ti 3- x C 2 T 2 HD achieves ultra-low Pt loading (1.16 wt.%) with low overpotential (42 mV @ −10 mA cm –2 ) and stable operation for 100 h at −50 mA cm –2 . • Strong Pt-Ti interaction and vacancy-induced charge redistribution optimize ∆G H * and d -band center, boosting activity. Engineering metal-support interactions at the atomic scale is critical for maximizing noble-metal utilization in hydrogen evolution electrocatalysis. Here, we report a defect-driven self-reduction strategy that exploits intrinsic Ti vacancies in Ti 3- x C 2 T 2 MXene to induce spontaneous reduction and atomic stabilization of Pt without external reducing agents. The vacancy-rich MXene framework simultaneously serves as an electron reservoir and anchoring template, enabling atomic-scale Pt dispersion at an ultra-low loading of 1.16 wt.%. The optimized Pt/Ti 3- x C 2 T 2 HD catalyst demonstrates excellent HER activity and durability in 0.5 M H 2 SO 4 , requiring low overpotentials of 42 and 95 mV at -10 and -100 mA cm –2 , respectively, while delivering enhanced mass activity and turnover frequency 8.7 and 8.5 times higher than commercial Pt/C and maintaining stable operation at -50 mA cm –2 for 100 h. DFT calculations reveal that Pt substitution at Ti vacancies of MXene generates abundant Pt-Ti-Ti threefold hollow sites with near-thermoneutral hydrogen adsorption free energies (∆G H *≈ -0.02 eV), while Pt-Ti d-orbital hybridization and directed charge transfer synergistically optimize the electronic structure, balancing hydrogen adsorption-desorption kinetics. This work highlights defect engineering of MXenes for support mediated noble-metal reduction and provides a rational design strategy for atom-efficient HER electrocatalysts. Pt atoms are atomically anchored on Ti vacancies of MXene via a defect-driven self-reduction strategy, achieving an ultra-low loading of 1.16 wt.% with a low overpotential of 42 mV at -10 mA cm –2 and 100 h stability at -50 mA cm –2 , attributed to the intrinsic Ti vacancies serving as both anchoring sites and electron donors for spontaneous Pt reduction. Download: Download high-res image (323KB) Download: Download full-size image