Dual-Fullerene-Confined Single Transition Metal Atoms as High-Efficiency Catalysts for Hydrogen Evolution Reaction

Abstract

The hydrogen evolution reaction (HER) is crucial to the production of green hydrogen via water electrolysis. Recent experimental work has shown that platinum atoms confined within two C₆₀ molecules, forming Pt@(C₆₀)₂, exhibit exceptional HER activity. To systematically explore this class of single−atom catalysts, density functional theory (DFT) calculations were employed to screen 26 transition metal (TM) centers anchored by dual−fullerene C₆₀ cages. Gibbs free energy calculations revealed that the single−atom catalysts including Sc@(C₆₀)₂, Ti@(C₆₀)₂, Fe@(C₆₀)₂, Co@(C₆₀)₂, Y@(C₆₀)₂, Zr@(C₆₀)₂, and Ta@(C₆₀)₂ demonstrate outstanding catalytic performance. Interaction characteristics between metals and substrates, as well as between metals and adsorbed hydrogen atoms was further elucidated through electronic−structure analyses including partial density of states (PDOS), charge density difference (CDD), and crystal orbital Hamilton population (COHP). This study also reveals that H₂O adsorption and dissociation is exothermic for most species, which holds an advantage in the water activation stage for alkaline HER. The reaction pathway for H₂ production over TM@(C₆₀)₂ is identified as the Tafel pathway, owing to its lower energy barriers compared with the Heyrovsky pathway. This work confirms that the dual−fullerene C₆₀ functions as both an effective support for single−atom TM and a promoter of high HER activity, providing a theoretical basis for designing novel fullerene-based single-atom catalysts and expands the role of zero-dimensional carbon materials in energy applications.