Heterobimetallic [NiCo] integration in a hydrogenase mimic for boosting light-driven hydrogen evolution in CaTiO₃

Light-drive hydrogen production using titanium-based perovskite is one sustainable way to reduce current reliance on fossil fuels, but its wide applications are still limited by high electron-hole recombination and sluggish surface reaction. Thus, the developments for low-cost and highly efficient co-catalysts remain urgent. Inspired by natural [NiFe]-hydrogenase active center structure, a hydrogenase-mimic, NiCo₂S₄ nanozyme was synthesized, and subsequently decorated onto the CaTiO₃ to catalyze the hydrogen evolution reaction (HER). Among the following test, CaTiO₃ with a 15% loading of NiCo₂S₄ nanozyme exhibited the highest HER rate of 307.76 μmol·g^-1·h^-1, which is 60 times higher than that of the CaTiO₃ alone. The results revealed that NiCo₂S₄ not only significantly increased the charge separation efficiency of the photogenerated carriers, but also substantively lowered the HER activation energy. Mechanism studies show that NiCo₂S₄ readily splits H₂O by forming the Ni(OH)-Co intermediate and only Ni in the bimetallic center alters the oxidation state during the HER process in a manner analogous to the [NiFe]-hydrogenase. In contrast to the often-expensive synthetic catalysts that rely on rare elements such as ruthenium or platinum, this study shows a promising way to develop the nature-inspired cocatalysts to enhance the photocatalysts’ HER performance.