Gram‐Scale Green‐Synthesis of High Purity Pinacols and Amides by Continuous Tandem Photocatalysis via a Negative Carbon Emission Process

Abstract

Abstract Solar‐driven CO 2 reduction for practical applications confronts significant challenges, including the waste of oxidation power and the difficulty in isolating reduction products. Herein, a pre‐coordination restriction strategy is presented to hierarchically assemble CdS quantum dots (QDs), cobalt sites and Zr 6 clusters in one metal–organic framework (MOF), resulting in the CdS@PCN‐Co composite for simultaneous CO 2 photoreduction and C–C coupling. Impressively, the yields of CO and pinacols with CdS@PCN‐Co can reach 59.5 mmol·g⁻¹ (99.4% selectivity) and 56.2 mmol·g⁻¹ (95.3% selectivity), respectively, over six and seven times higher than those with the CdS/PCN‐Co mixture (9.8 mmol•g⁻¹ CO, 29.4% selectivity; 7.8 mmol•g⁻¹ pinacols, 22.7% selectivity). The superior catalytic performance of CdS@PCN‐Co can be ascribed to the synergy among encapsulated CdS QDs, Zr 6 clusters and PCN‐Co, where photogenerated electrons can efficiently transfer from CdS QDs to Co sites for selective CO generation while the remaining holes can oxidize the adsorbed 1‐phenylethanol over Zr 6 surface to facilitate C–C coupling. More impressively, the released CO can be immediately used for carbonylation photosynthesis by immobilizing CdS@PCN‐Co and Pd/PCN‐Zn in a continuous‐flow system with two reactors, which simultaneously achieves gram‐scale photosynthesis of high‐purity pinacols and amides by continuous tandem photocatalysis.