Synergistic Engineering of Electron-Enriched Nickel Sites for Highly Efficient Photocatalytic CO₂ Reduction to C₂H₆

The production of multi-carbon compounds through CO₂ photoreduction (CO₂PR) holds great promise but faces challenges due to high kinetic barriers and the sluggish process of C-C coupling. Overcoming these obstacles requires fine engineering of active sites. In this study, Ni active sites are engineered through the synergistic effect of metal-oxo cluster (Mo₇O₂₄⁶⁻) and hydroxyl vacancy (V_OH). In contrast to the Ni sites unmodified with Mo₇O₂₄⁶⁻ and V_OH, which are unable to produce multi-carbon products, the constructed electron-enriched Ni active sites exhibit an impressive selectivity of up to 43.02% and a high yield rate of 246.70 µmol g⁻¹ h⁻¹ for C₂H₆, which represent one of the best results for CO₂PR to C₂H₆. Through a comprehensive investigation involving operando experiments and theoretical simulations, hydroxyl vacancy and the formed Mo─O─Ni bonds is demonstrated due to the filling of hydroxyl vacancies with oxygen atoms from Mo₇O₂₄⁶⁻ synergistically constructed electron-rich Ni sites. Such Ni sites efficiently catalyze CO₂ conversion to C₂H₆ by enhancing the adsorption of ^*CO, promoting subsequent hydrogenation, and enabling low energy barriers for CO₂ hydrogenation to ^*OCOH and the coupling of ^*CH₃ intermediates. This study provides deeper insights into the photocatalytic process, highlighting the significance of tailored active sites for efficient CO₂ conversion. © 2024 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH.