Light-Induced Synthesis of Oxygen-Vacancy-Functionalized Ni(OH)₂ Nanosheets for Highly Selective CO₂ Reduction

Solar-driven CO₂ reduction into fuels and chemicals has gained increasing attention in recent years. In this study, oxygen-vacancies-functionalized Ni(OH)₂ (OVs-Ni(OH)₂ ) nanosheets are synthesized by a photochemical method to serve as a catalyst for CO₂ reduction. Characterization reveals that COOH* is the key intermediate for CO₂ -to-CO photoreduction. Experimental results and theoretical calculations confirm that OVs modification can greatly modulate the interaction strength between the OVs-Ni(OH)₂ and CO₂ , while lowering the energy barrier for COOH* formation, thereby preferentially facilitating CO₂ reduction. As a result, the OVs-Ni(OH)₂ catalyst exhibits outstanding activity and selectivity for CO₂ -to-CO photoreduction with visible light. A CO evolution rate of 31.58 μmol h^-1 (0.35 mg catalyst, 90228 μmol h^-1  g^-1 ) with a selectivity of 98 % over OVs-Ni(OH)₂ was achieved, outperforming most analogous reported catalysts. Moreover, even under a low CO₂ concentration of 0.04 % (representative of the CO₂ concentration in air) and low reaction temperature (273 K, 0 °C), this catalyst can still trigger CO₂ reduction. This work provides a new method to synthesize OVs-Ni(OH)₂ catalysts for efficient CO₂ reduction and establishes a relationship between the OVs and the catalytic activity, which may guide the design of highly selective CO₂ reduction catalysts.