Green Synthesis of\nAmorphous Ni–Fe Oxyhydroxide\nNanosheets for Oxygen Evolution

Metal oxyhydroxides have been considered efficient electrocatalysts\nfor the oxygen evolution reaction (OER), and structural flexibility\nhas a significant role in boosting catalytic performance. However,\nstructural control usually requires time-consuming and complicated\nsynthesis stages. Here, a rapid one-step wet-chemical synthetic approach\nis reported to construct amorphous NiFeOOH nanosheets (a-NiFe<sub><i>x</i></sub> NSs). This short-term, low-cost method can\nefficiently control the crystallinity of the materials. Interestingly,\none can regulate the oxygen defect concentration and the metal valence\nby varying the Ni/Fe ratio. The high-valence metal species and oxygen\nvacancy in the amorphous structure facilitate the nucleophilic attack\nof OH<sup>–</sup>, activate lattice oxygen, and promote electrocatalytic\nperformance. The optimized a-NiFe<sub>0.86</sub> NS exhibits superior\nelectrocatalytic performance with a low overpotential of 309 mV to\nachieve 100 mA cm<sup>–2</sup> and high stability. This strategy\nprovides a facile and universal approach to fabricating amorphous\nNiFe-based oxyhydroxides as highly efficient OER electrocatalysts.