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.