In situ Raman Monitoring\nof Surface Structures and\nOxygen Species on Ni(OH)<sub>2</sub>/Au/Nickel Foam During Oxygen\nEvolution Reaction

Nickel foam is a prevalent material for the oxygen evolution\nreaction\n(OER) in alkaline media. Herein, we employed a one-step electrodeposition\ntechnique to effectively fabricate a Ni(OH)<sub>2</sub>/Au/nickel\nfoam (denoted as a Ni(OH)<sub>2</sub>/Au/NF) catalyst. This catalyst\nexhibits both surface-enhanced Raman scattering (SERS) activity and\ncatalytic activity. The electrochemical SERS technique is employed\nfor in situ monitoring of surface structure changes and intermediates\nduring the OER process. The molecular evidence reveals that the electro-driven\ninitial Ni(OH)<sub>2</sub> first becomes disordered and finally is\noxidized to NiOOH. When the OER occurs, the active oxygen species\nof NiOO* is observed to release O<sub>2</sub>. Compared with that\nof bare NF, the more disordered NiOOH from Ni(OH)<sub>2</sub>/Au/NF\nhas a greater OER activity. These findings significantly advance the\nunderstanding of the OER mechanism on Ni-based catalysts, providing\nguidelines for the elaboration and optimization of future catalytic\nsystems.