Strain-Controlled Pt Single-Atom Catalysts on Crumpled MXene Supports for Highly Active Hydrogen Evolution.

Abstract

Strain engineering offers a powerful means to regulate the electronic structure and catalytic behavior of active metal sites, yet a general framework linking strain to electrocatalytic performance remains elusive beyond the conventional d-band model. Here we report crumpled double-transition-metal MXene nanosheets (Mo2TiC2Tx) decorated with Pt single atoms, in which a tunable strain field is introduced through a physical diaphragm balloon method. The resulting cMo2TiC2Tx-PtSA catalyst exhibits outstanding alkaline hydrogen evolution performance, requiring overpotentials of only 24.9 and 75.5 mV to reach 10 and 50 mA cm-2, respectively, together with a mass activity of 11 859 mA mgPt-1, around 178-fold higher than commercial Pt/C, a Tafel slope of 31.61 mV dec-1 and excellent durability. In situ spectroscopy and density functional theory calculations show that the ordered long-range strain field around isolated Pt sites accelerates interfacial water activation while preserving near-optimal H adsorption, thereby facilitating H2 release. The resulting catalyst delivered a high current density of 3 A cm-2 at a low voltage of 1.98 V and maintained stable operation at 1000 mA cm-2 for over 500 h. These performance metrics underscore the potential of cMo2TiC2Tx-PtSA for industrial applications.