Origin of hydrogen evolution activity of single-atom metals anchored on Stone-Wales defective graphene: a...

Efficient, low-cost, and stable electrocatalysts are critical for sustainable hydrogen production. In this work, single transition metal (TM) atoms anchored on Stone-Wales defect graphene (SW-G) were investigated using density functional theory (DFT) calculations. SW defects provide stable anchoring sites, modulating the electronic structure and hydrogen adsorption behavior of graphene. Among the studied systems, V@SW-G, Mn@SW-G, Ni@SW-G, Cr@SW-G, and Rh@SW-G show Gibbs free energies of hydrogen adsorption (ΔG_H*) near zero, indicating favorable HER activity. Electronic structure analysis reveals that strong metal-substrate interactions and defect-induced charge transfer weaken the direct correlation between the d-band center and ΔG_H*, while the d-band center-Bader charge relationship highlights the role of electronic reconstruction. Kinetic analysis further shows that different TM@SW-G catalysts preferentially follow distinct HER pathways. This work provides mechanistic insights into defect-regulated single-atom catalysis and guides the rational design of high-performance graphene-based HER catalysts.