Green Synthesis of Amorphous Ni–Fe Oxyhydroxide Nanosheets for Oxygen Evolution

Metal oxyhydroxides have been considered efficient electrocatalysts for the oxygen evolution reaction (OER), and structural flexibility has a significant role in boosting catalytic performance. However, structural control usually requires time-consuming and complicated synthesis stages. Here, a rapid one-step wet-chemical synthetic approach is reported to construct amorphous NiFeOOH nanosheets (a-NiFex NSs). This short-term, low-cost method can efficiently control the crystallinity of the materials. Interestingly, one can regulate the oxygen defect concentration and the metal valence by varying the Ni/Fe ratio. The high-valence metal species and oxygen vacancy in the amorphous structure facilitate the nucleophilic attack of OH–, activate lattice oxygen, and promote electrocatalytic performance. The optimized a-NiFe0.86 NS exhibits superior electrocatalytic performance with a low overpotential of 309 mV to achieve 100 mA cm–2 and high stability. This strategy provides a facile and universal approach to fabricating amorphous NiFe-based oxyhydroxides as highly efficient OER electrocatalysts.