Self-Supported Porous Ni–Fe–W Hydroxide Nanosheets on Carbon Fiber: A Highly Efficient Electrode for Oxygen Evolution Reaction

Structural and compositional modulation of low-cost hydroxide is important for making efficient electrocatalysts of the oxygen evolution reaction (OER), and it is an ongoing challenge. Here, Ni–Fe–W hydroxide complex by incorporation of tungsten into nickel–iron layered double hydroxide was proposed and investigated. As-formed Ni–Fe–W hydroxide nanosheets are highly porous and self-supported on the carbon fiber substrates, which promote the exposure of the active metal sites for significantly enhanced OER activity. Moreover, the as-introduced tungsten is evidenced to be in a W6+ oxidation state which can facilitate charge transfer and electron capture and thereby decrease the critical conversion barrier of the absorbed OH– to O radical in OER. A series of Ni–Fe–W hydroxides were prepared, with the best molar ratio of Ni–Fe–W sources being 6:2:1. The optimal Ni6Fe2W-LDH@carbon fiber electrode delivers a low overpotential of 264 mV at 10 mA cm–2 and high stability (only 1.6% of the potential increase after 10 h) in alkaline electrolyte. Moreover, the structure of the constructed Ni–Fe–W hydroxide is evidenced to be stable and important for the electrocatalytically stable. The study is expected to open a new avenue in developing multiple hydroxides for low-cost and efficient electrocatalysts.