Toward Molecular Level Understandings of Hydrogen Evolution Reaction on Platinum Surface

The electrocatalytic hydrogen evolution reaction (HER) is of central importance for water electrolysis and green hydrogen production. Platinum represents the state-of-the-art electrocatalyst for the HER. The HER on the platinum surface displays distinct pH dependent kinetics, showing much more sluggish kinetics in alkaline media than in acidic electrolytes. The fundamental origin of the pH-dependent HER kinetics has attracted substantial interest in the electrocatalysis community. Considerable efforts have been made to understand the distinct HER kinetics in different electrolytes, although with frequent inconsistencies among different studies. A fundamental molecular level understanding of the pH dependent HER kinetics remains elusive but is essential for developing more efficient and cost-effective water electrolysis technologies. This Perspective summarizes the current status of the mechanistic understanding of HER on platinum surface, analyzes several intertwined factors that could alter the fundamental molecular pathways and reaction kinetics in different electrolytes, and highlights the challenges and opportunities associated with advancing the mechanistic understanding of HER on platinum surface.