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

Abstract

Solar‐driven CO2 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 Zr6 clusters in one metal–organic framework (MOF), resulting in the CdS@PCN‐Co composite for simultaneous CO2 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, Zr6 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 Zr6 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.