Regulating the electronic structure of catalysts via stable ceria and adjustable copper metal/oxide towards efficient overall water splitting

Designing efficient, economical bifunctional electrocatalysts for overall water splitting is important and challenging. This paper demonstrates a cobalt-based electrocatalyst modified with stable ceria (CeO2) and adjustable copper metal/oxide (Cu/CuO) to regulate electrochemical reconfigurations during the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Theoretical calculations reveal that CeO2 substantially impacts the electronic configuration and D-band center of catalysts. Surprisingly, CeO2 moves the D-band center of cobalt oxyhydroxide closer to the Fermi level but shifts the D-band center of cobalt hydroxide away from the Fermi level. Therefore, CeO2 optimizes the adsorption energy of the intermediates and boosts the OER activity, while reducing the ability of absorbed hydrogen atoms to bond with the catalyst and enhancing the electron-donor performance of the catalyst in the HER. Furthermore, the presence of Cu/CuO dramatically improves the catalytic activity. Hence, the utilization of CeO2 and CuO/Cu in cobalt-based nanosheet arrays enhances catalytic efficiency in overall water splitting. The overpotentials are only 94 mV and 246 mV (@10 mA cm-2) for the HER and OER, respectively, superior to those of pure cobalt-based catalysts. This study presents an innovative approach to developing efficient overall water splitting catalysts and offers insights into future developments in this field.