In-situ Growth of Scalable Low-Crystalline γ-FeOOH@Ni(OH)2 Nanosheet Heterostructured Catalysts for Stable Oxygen Evolution Reaction at Large Current Density

Transition metal hydroxides have the advantage of high activity and low cost in alkaline electrolytes and are considered one of the most promising catalysts for anodic oxygen evolution reaction (OER). However, single nickel or iron hydroxides is unstable during the reaction process and have a tendency to agglomerate and poor electrical conductivity. Therefore, we designed a kinetically controlled liquid-phase method to synthesize scalable low-crystalline γ-FeOOH@Ni(OH)2 nanosheet arrays on nickle foam (NF) in an open environment. By adjusting the alkalinity and reaction time, we systematically investigated the formation process and the potential mechanisms related to the structural evolution of γ-FeOOH@Ni(OH)2 catalysts. γ-FeOOH@Ni(OH)2 was used as an OER catalyst and showed excellent hydrolytic activity and stability, with a stable operation of more than 320 h at a large current density of 500 mA cm–2. Density functional theory calculations show that the synergistic effect of γ-FeOOH and Ni(OH)2 increases the charge accumulation near the Fermi energy level, thus increasing the chance of electron transfer and effectively facilitating the decomposition of water molecules. This work provides a new strategy for the design and exploration of catalysts for achieving large-scale industrialized water decomposition for hydrogen production in an open environment.