Vacancy-Defect Single-Atom Catalysts for Tandem CO2 Electroreduction and Carbonylation Reactions from Flue Gas.

Tandem CO₂ reduction with carbonylation reactions represents a promising approach to convert greenhouse gases into valuable chemicals. Herein, we propose a universal "N/O mixed pre-coordination pyrolysis" strategy to construct vacancy-defect single atom catalysts (Ni₁-, Mn₁-, Fe₁-, Co₁-, and Cu₁-NC) with M-N₃ coordination microenvironment. This vacancy-defect endows Ni₁-NC with excellent performance for CO₂ electroreduction, achieving a CO faradaic efficiency exceeding 90% across a wide range of current densities up to 300 mA cm^-2. The generated CO was directly fed to carbonylation reactions, producing organic chemicals with yields of up to 91.7% and leading to produce 1.13 g of benzophenone in a single run. For the first time, the membrane separation CO₂ system was integrated with tandem catalytic system, enabling direct utilization of flue gas for benzophenone synthesis with a 76.6% yield. This work offers a sustainable, eco-friendly method for CO₂ separation and utilization by feeding industrial waste gas to carbonylation reactions.