Sulfur-Enhanced Anchoring of Pt and Co Nanoparticles on N-Doped Porous Carbon for High-Current Hydrogen Evolution

The widespread application of platinum (Pt)- and cobalt (Co)-based electrocatalysts for alkaline hydrogen evolution reaction (HER) is constrained by the agglomeration and corrosion of metal nanoparticles under high current density and prolonged operating conditions. To address these challenges, this work presents an innovative S-doping strategy, wherein S atoms are integrated into nitrogen-doped carbon matrices derived from metal-organic frameworks, thereby enhancing the metal-support interactions. The incorporation of S provides abundant anchoring sites that enable uniform dispersion of Pt and Co nanoparticles, effectively preventing particle agglomeration. Electrochemical measurements demonstrate that Pt/Co@S-N-C exhibits an ultra-low over potential of 16 mV at a current density of 10 mA·cm^-2, outperforming commercial Pt/C (25 mV). In a membrane-electrode assembly (MEA) system, the cell delivers 1000 mA·cm^-2 at 1.80 V and exhibits minimal voltage drift over 72 h (ΔV_72h = 11 mV), whereas Pt/Co@N-C shows a 147 mV increase under identical conditions. Density functional theory (DFT) calculations show that S doping induces a local ligand effect which tunes the Pt electronic structure, promotes interfacial water adsorption and dissociation, and thereby facilitates the Volmer step in alkaline HER. This work provides an effective strategy for developing stable electrocatalysts for alkaline HER under high-current-density.