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

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 V CO) 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 V CO) 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 V CO 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.