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.
Keywords: CO2 reduction; defect engineering; nanostructures; nickel; photocatalysis.
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