Electronic structure engineering of NiFe hydroxide nanosheets via ion doping for efficient OER electrocatalysis

Abstract

Nickel-iron layered double hydroxides (NiFe-LDH) with tunable catalytic properties have shown promise as an outstanding alternative to ruthenium iridium oxide for the oxygen evolution reaction (OER). However, the intrinsic activity of such electrocatalysts is suboptimal, and a considerable gap remains in understanding the working mechanism. To address this issue, we employ a convenient corrosion method to synthesize Mo-modified nickel–iron hydroxide (Mo-NiFeOxHy) ultrathin nanosheets. Mo-NiFeOxHy demonstrates excellent OER activity, requiring only 216 mV at a current density of 10 mA cm−2, with enhanced stability. Theoretical calculations reveal that the Mo doping induces material distortion, shifting the d-band center closer to the Fermi level, which accelerates the kinetic rate and catalytic activity. In situ Raman experiments show that doping with Mo promotes the rapid formation of high-oxidation-state transition metal hydroxide species, further enhancing the catalytic properties of Mo-NiFeOxHy in OER. This work provides a novel strategy to tailor the structure and composition of NiFe-based electrocatalysts, demonstrating a great potential to break barriers in OER.