Amorphous High-Entropy Borides Ensuring High Activity and Stability toward Efficient Water Oxidation

To address the imbalance issue between the water oxidation activity and stability of catalysts via the lattice oxygen oxidation mechanism (LOM), this study reports the rational design of an amorphous high-entropy catalyst (HEB-CTS) for efficient water oxidation. HEB-CTS is characterized by multielement synergy, intrinsic amorphous structure, and abundant oxygen vacancies. The oxygen vacancies resulting through the carbon thermal shock (CTS) technique inhibit excessive leaching of alkali-soluble elements (Mo, Zn) in HEB-CTS, which mitigates the loss of active components caused by excessive surface reconstruction. Density function calculation reveals that the p-orbitals of oxygen on the reconstructed catalyst surface exhibit stronger hybridization with the d-orbitals of active elements (Ni, Co), thus enhancing the covalent M–O bonding and promoting direct O–O coupling of lattice oxygen to generate O2 via LOM. Additionally, the charge redistribution between the reconstructed active MOOH layer and the bulk HEB-CTS facilitates the rapid replenishment of surface OH–. Under such a design, HEB-CTS achieves an overpotential of only 250 mV at 10 mA cm–2 and maintains stable water oxidation for over 550 h at 100 mA cm–2, significantly outperforming commercial RuO2 and some reported high-entropy benchmark materials. This study provides a novel strategy for developing highly efficient and stable LOM-based high-entropy amorphous catalysts for water oxidation.