A Unique Etching‐Doping Route to Fe/Mo Co‐Doped Ni Oxyhydroxide Catalyst for Enhanced Oxygen Evolution Reaction

Abstract Fe‐doped Ni (oxy)hydroxide shows intriguing activity toward oxygen evolution reaction (OER) in alkaline solution, yet it remains challenging to further boost its performance. In this work, a ferric/molybdate (Fe3+/MoO42−) co‐doping strategy is reported to promote the OER activity of Ni oxyhydroxide. The reinforced Fe/Mo‐doped Ni oxyhydroxide catalyst supported by nickel foam (p‐NiFeMo/NF) is synthesized via a unique oxygen plasma etching‐electrochemical doping route, in which precursor Ni(OH)2 nanosheets are first etched by oxygen plasma to form defect‐rich amorphous nanosheets, followed by electrochemical cycling to trigger simultaneously Fe3+/MoO42− co‐doping and phase transition. This p‐NiFeMo/NF catalyst requires an overpotential of only 274 mV to reach 100 mA cm−2 in alkaline media, exhibiting significantly enhanced OER activity compared to NiFe layered double hydroxide (LDH) catalyst and other analogs. Its activity does not fade even after 72 h uninterrupted operation. In situ Raman analysis reveals that the intercalation of MoO42− is able to prevent the over‐oxidation of NiOOH matrix from β to γ phase, thus keeping the Fe‐doped NiOOH at the most active state.