Molecular Probing Coupled with Density Functional Theory Calculation to Reveal the Influence of Fe Doping on Fe-NiOOH Electrode for High Current Density of Water Splitting

Abstract

Fe-doped NiOOH electrocatalysts have attracted wide interest for the exceptional oxygen evolution reaction (OER) performance, but the precise role of Fe doping on the improved intrinsic activity remains unclear. Herein, the molecular probe technique combined with density functional theory calculation is used to reveal the influence of the Fe atom on the rate-determining step of the OER reaction, where the pre-catalyst of hierarchical self-supporting NiFe layered double hydroxide [LDH] nanosheets equipped on nickel foam (NiFe LDH/NF) is generated via a facile and industrially well-matched one-pot corrosion method. The physical characterization results reveal the reconstruction of NiFe LDH into Fe-doped NiOOH for promoted OER, which has a lower OH* adsorption energy with fast subsequent steps that help in obtaining an improved charge injection efficiency compared to NiOOH. In addition, more exposed electroactive species and facile delivery of mass/electron inside the catalytic procedure actually have a high-quality contribution to the outstanding catalytic activity. Therefore, the NiFe LDH₃₆/NF electrocatalyst provides high catalytic activities of 241 and 320 mV at 10 mA cm⁻² toward the OER and overall water-splitting in 1 m KOH. This work provides a promising avenue for the rational design of durable self-supporting electrodes toward large-scale water splitting.