Simultaneous phase transformation and doping via a unique photochemical–electrochemical strategy to achieve a highly active Fe-doped Ni oxyhydroxide oxygen evolution catalyst

Abstract

NiFe based (oxy)hydroxides demonstrate promising electrocatalytic activity toward the oxygen evolution reaction (OER) in alkaline media. To further improve their electrocatalytic performance, it is critical to maximize the density of active sites on the surface while maintaining a high structural order level of the NiOOH host. In this work a unique photochemical–electrochemical strategy is reported to fabricate an active Fe-doped Ni oxyhydroxide electrocatalyst on a three-dimensional carbon cloth scaffold (Fe–NiOOH@CC). Raman depth profiling suggests abundant Fe-containing active sites on the surface of the NiOOH matrix, and NiOOH itself remains highly crystalline with a low structural disorder level in the as-synthesized Fe–NiOOH@CC. Due to this compelling property, it exhibits higher OER catalytic activity than RuO₂ and other NiFe analogues and maintains its activity for at least 55 h at ∼150 mA cm⁻². This photochemical–electrochemical method is applicable to other transition metals and substrates, thus offering a unique while universal strategy for synthesis of OER electrocatalysts.