Modulating interfacial charge density of FeCo oxyhydroxides via coupling with graphene oxide aerogel for boosting oxygen evolution reaction

Abstract

Given the sluggish kinetics limiting the oxygen evolution reaction (OER), developing efficient and robust OER catalysts is highly demanded in developing efficient energy conversion technologies. Herein, we have grown FeCo oxyhydroxides on the 3D graphene oxide (GO) framework (FeCo2Ox(OH)y/GO) via a simple sol-gel process, combined with the supercritical drying technique. The resulting FeCo2Ox(OH)y/GO aerogel-based electrocatalyst possesses high porosity and a large BET specific surface area with 223.52 m2/g, which exposes more active sites, as well as provides diffusion channels for the reaction products. The resulting electrocatalyst requires an overpotential of 305 mV at a current density of 10 mA cm−2, with a low Tafel slope (43.7 mV dec−1) and excellent stability, which indicates superior OER catalytic activity to that of the commercial RuO2/C under alkaline conditions. Based on density functional theory (DFT) calculations, the synergistic effect between the GO layer and FeCo oxyhydroxides layer has been revealed by the electronic structures calculations. The incorporation of GO results in a negative shift of the d-band center of the surface active sites, indicating a decrease in the binding strength between the catalyst surface and the intermediates, therefore accelerating the OER process.