Alleviating the strong hydrogen-bonded interfacial water structure on amorphous Mn-doped RuSe2 nanoparticles deposited on wood-derived carbon for efficient acidic hydrogen evolution.

The surficial water structure in the electrode/electrolyte double layer governs the transfer rate of protons during the acidic hydrogen evolution reaction (HER). Herein, we introduce the novel strategy to alleviate the strong hydrogen-bonded water structure by doping Mn in the amorphous RuSe2 nanoparticles deposited on wood-derived carbon for efficient acidic HER. The optimized amorphous (Ru97.7Mn2.3)Se2 catalyst requires only 299 mV to deliver 1 A cm-2 in 0.5 M H2SO4 electrolyte, which is comparable to that of the benchmarking commercial Pt/C (20 wt%), and maintains outstanding durability for 100 h at a current density of 100 mA cm-2. Furthermore, an acidic photovoltaic-driven overall water-splitting system employing amorphous (Ru0.67Mn0.33)Se2 catalyst as the cathode achieves a solar-to‑hydrogen energy conversion efficiency of 7.95%. In situ Raman spectra reveal that Mn incorporation reconstructs the interfacial water environment by alleviating the strong hydrogen-bonded interfacial water structure, thereby facilitating protons transfer. Density functional theory (DFT) calculations illuminate that Mn doping induces the upshifting of the d-band center of Ru in amorphous RuSe2, which leads to the optimized *H adsorption/desorption thermodynamics. These results demonstrate the synergistic effects of electronic structure regulation and interfacial water structure reconstruction on the amorphous (Ru97.7Mn2.3)Se2 catalyst enabling the efficient acidic HER and solar-driven green hydrogen production.