Defect-Induced Electron Redistribution between Pt-N₃S₁ Single Atomic Sites and Pt Clusters for Synergistic Electrocatalytic Hydrogen Production with Ultra-High Mass Activity

A N, S co-doped carbon with abundant vacancy defects (NSC) anchored Pt single atoms (SAs) and nanoclusters (NCs) derived from coal pitch by a self-assembly-pyrolysis strategy is reported and a defect-induced electron redistribution effect based on Pt SAs-Pt NCs/NSC catalyst is proposed for electrocatalytic hydrogen evolution reaction (HER). The optimized catalyst featuring Pt-N₃S₁ SAs and Pt NCs dual active sites exhibit excellent HER activity with an overpotential of 192 mV at a current density of 400 mA cm⁻², a turnover frequency of 30.1 s⁻¹ at an overpotential of 150 mV, which the mass activity is 13716 mA mg_Pt⁻¹, 7.4 times higher than that of 20% Pt/C catalyst. In situ Raman revealsa direct correlation between the defect structure of the catalyst and hydrogen adsorption during the reaction process. Density functional theory calculation shows the defect-induced electron redistribution between Pt-N₃S₁ SAs and Pt NCs. The electrons are transferred from Pt NCs to Pt SAs, which increases the number of electrons on the surface of Pt SAs and enhances the adsorption ability of H⁺. Meanwhile, the dissociation ability of H* on the Pt NCs is promoted, thus synergistically promoting the HER process.