Ultra‐Stable Ti Vacancies‐Pt Atomic Clusters Structure on Titanium Oxycarbide Supports for High Current Density Hydrogen Evolution Reaction

Abstract Electrocatalysts with low Pt loading mass to achieve high current density (≥1 A cm⁻²) for hydrogen evolution reaction (HER) are still extremely challenging due to the limited intrinsic activity and weak stability of catalytic sites. The modulation of the electronic microenvironment of the support‐Pt structure is crucial to enhance the intrinsic activity and stability of catalytic sites. Herein, an innovative titanium oxycarbide (Ti_VCO) solid solution with Ti vacancies (Ti_V) is proposed as support to anchor sub‐nanoscale Pt atomic clusters (Pt ACs) and a stable “Ti_V‐Pt ACs” structure is carefully designed. The electronic microenvironment of “Ti_V‐Pt ACs” is indirectly optimized by an unsaturated C/O site near Ti_V. Thanks to this, novel “Ti_V‐Pt ACs” structure (Pt@Ti_VCO) with low Pt loading mass (2.44 wt.%) exhibits excellent HER activity in acidic solution and the mass activity is more than ten times that of commercial 20% Pt/C at the overpotentials of 50 and 100 mV. Particularly, Pt@Ti_VCO shows amazing stability at high and fluctuating current density of 1–2 A cm⁻² for 120 h. This work provides a novel and promising method to develop stable and low‐loading Pt‐based catalysts adapting to high current density.