Unveiling Hydrogen Passivation Effects in TiC-Based Single-Atom Catalysts for Enhanced Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) is crucial for producing hydrogen gas via electrochemical water splitting. Among diverse strategies to activate the HER, single-atom catalysts (SACs) are efficient alternatives to conventional platinum catalysts, focusing on titanium carbide (TiC) as a support material with good redox and electronic stability. Using this, we conducted a comprehensive investigation of various SAC candidates, screening their thermodynamic stabilities and HER activities. These calculations revealed four possible transition metal (TM) (Pt, Pd, Au, and Ag)-embedded TiC candidates (TM@TiC) that are thermodynamically stable and further suggested that they exhibit an intriguing H*-passivated surface state, significantly improving HER activities. Notably, the Pt@TiC demonstrates superior activity, promoting H₂ gas generation due to its unique H*-passivated surface, which enables a sustainable HER. Therefore, this work introduces a new SAC paradigm centered around the H*-passivated surface, expanding the conventional focus on a single TM site.