Controlled Atmosphere Corrosion Engineering toward Inhomogeneous NiFe-LDH for Energetic Oxygen Evolution

The "Fe effect" can maximize the activity of nickel-iron layered double hydroxides (NiFe-LDH) toward oxygen evolution reaction (OER) when the iron content, the lattice distortion, the conductivity, and other related factors are well balanced. It is difficult for the homogeneous NiFe-LDH to take good care of the above requirements at the same time. Herein, we proposed an elaborate atmosphere corrosion strategy to construct porous NiFe-LDH with rich edge/surface-Fe defects on Ni foam (NF). Such edge/surface-Fe defects, mainly caused by the local unequal-stoichiometric ratio of Fe/Ni in the nanometer or subnanometer region, are determined by the unbalanced permeating of the acid vapor and the confined reaction of local Fe and Ni species ionized by the acid vapor. Benefiting from the abundant and fantastic edge/surface-Fe defects, the optimal NiFe-LDH prepared by atmosphere corrosion is more energetic for OER than that synthesized in conventional liquid phase, only a potential of 1.481 and 1.552 V_RHE to respectively achieve the current density of 100 and 1000 mA cm^-2 as well as a satisfactory stability and reproducibility. An overall water-splitting system assembled by inhomogeneous NiFe-LDH and commercial Pt-C can reach a current density of 100 mA cm^-2 at a solar cell of 1.72 V. Additionally, the atmosphere corrosion is very suitable for the large-scale, green, and economic synthesis of metal-based catalysts with high enrichment of defects, highlighting its potential for device and industrial applications.