Yttrium doping-induced electronic structure and interfacial water modulation for alkaline hydrogen evolution

Clarifying interfacial water effects is vital for alkaline HER catalyst design. We solvothermally prepared Y-doped Co-MOF/NF, then fabricated optimized 10%Y-Co-MOF-0.5P/NF via low-temperature phosphidation. In situ tests indicate structural evolution of interfacial water driven by Y doping, while a plausible interpretation of d‑p‑d orbital coupling is put forward to rationalize the underlying electronic modulation. With more negative HER potential, 2-HBW decreases while 4-HBW and free H-down water increase. Synergistic interfacial water and electronic tuning expedite water splitting and proton transport. The catalyst only needs 24 mV overpotential at 10 mA cm −2 and 251 mV at 1 A cm −2 in 1 M KOH. This dual-regulation strategy guides non-precious MOF-derived phosphide HER catalysts.