The oxygen evolution reaction is essential in the solar production of chemical fuels, green hydrogen. Plasmonic metal-semiconductor systems can be potentially used for the production. Hot electrons generated by localized surface plasmon resonance are rapidly injected into the semiconductor, and concentrated hot holes oxidize water on the catalysts for oxygen evolution. Using Ni-modified Au/TiO₂, in situ electrochemical surface-enhanced Raman spectroscopy was performed over the pH range of 7–13. Significantly enhanced photocurrents at near-neutral conditions were generated with low-energy photons (1.58 eV). The results prove that nickel-based catalysts accelerated the four-electron multistep reaction via plasmon-assisted water oxidation.