Amorphization‐Induced d‐Orbital Rearrangement in Ultrathin CoO Nanosheets with Strong d‐p Interactions for Efficient CO2 Photoreduction

Abstract Photocatalytic CO 2 conversion into syngas presents a sustainable avenue for mitigating carbon emissions while generating value‐added fuels. However, sluggish charge carrier dynamics and weak, non‐specific interactions between catalytic sites and CO 2 molecules limit efficiency. Herein, ultrathin amorphous CoO nanosheets (a‐CoO) are reported that integrate structural and electronic advantages for enhanced CO₂ photoreduction. X‐ray absorption spectroscopy and density functional theory analyses reveal that amorphization partially transforms the local crystal field of Co from quasi‐octahedral to quasi‐tetrahedral coordination, resulting in a greater population of unpaired electrons in the frontier d ‐orbitals. This reconfiguration promotes electron injection from Co 3 d yz into the 2π* antibonding orbitals component of C 2 p x in CO 2 , which strengthens 3 d ‐2 p orbital hybridization and lowers the activation energy barrier. In situ spectroscopic further confirms that this orbital restructuring accelerates charge transfer from the Co center to CO 2 and facilitates its activation. Meanwhile, the ultrathin 2D architecture improves the separation and transport of photoexcited carriers. Consequently, vigorous bubbles are observed under visible light irradiation, with a total syngas evolution rate of 23.7 mmol g −1 h −1 (12.6 and 11.1 mmol g −1 h −1 for CO and H 2 , respectively) and an apparent quantum efficiency of 1.28% at 450 nm—≈8.7‐fold improvement over its crystalline counterpart.