Alleviating the strong hydrogen-bonded interfacial water structure on amorphous Mn-doped RuSe₂ nanoparticles...

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 (Ru_97.7Mn_2.3)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 (Ru_0.67Mn_0.33)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 (Ru_97.7Mn_2.3)Se₂ catalyst enabling the efficient acidic HER and solar-driven green hydrogen production.