Activating Co(OH)2 Active Sites by Coupled with V2O5 to Boost Highly Efficient Oxygen Evolution Reaction

Abstract

AbstractElectrocatalytic water splitting generated oxygen (O2) and hydrogen (H2) is a promising way to solve the energy crisis. Oxygen evolution reaction (OER) compared to hydrogen evolution reaction (HER) has slow kinetics hindering overall process. Recently, cobalt hydroxide (Co(OH)2) with high activity and stability for OER has attracted more attention. During the OER process, the Co2+ in Co(OH)2 is further oxidized to Co3+ and CoOOH species are true active sites. However, the low conductivity of Co(OH)2 hinders its oxidization to CoOOH. In addition, spontaneous growth of Co(OH)2 agglomerates easily during hydrothermal treatment, leading to decreased active sites. Herein, an efficient strategy is developed to construct highly dispersive Co(OH)2 nanosheets vertically grown on V2O5 nanoflowers (Co(OH)2/V2O5) at room temperature. The V5+ of V2O5 can oxidize Co2+ of Co(OH)2 into Co3+, resulting in in situ formations of CoOOH species favorable to the OER process. In situ Raman also investigates that the OH‐ species are inserted more easily into the interlayer of Co(OH)2 of (Co(OH)2/V2O5) than that of pure Co(OH)2. Therefore, the hybrid Co(OH)2/V2O5 exhibits low overpotentials of 320 and 370 mV at a current density of 10 and 50 mV cm‐2, respectively, and a small Tafel slope of 68 mV dec‐1.