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 reveal 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 and platinum, this study shows a promising way to develop the nature-inspired cocatalysts to enhance the photocatalysts’ HER performance.