In-situ polymerization induced atomically dispersed manganese sites as cocatalyst for CO₂ photoreduction into synthesis gas

Developing highly-active single atom catalyst to realize visible light driven photocatalytic CO₂ reduction into value-added chemicals is an appealing route toward utilizing CO₂ as the only carbon source for a sustainable future. Herein, we have successfully synthesized the atomically dispersed manganese sites in nitrogen doped carbon via an in-situ polymerization approach. The in-situ oxidative polymerization of pyrrole monomer directly catalyzed by manganese dioxide could extract the Mn atoms from MnO₂ and stabilize them within the as-generated polymer skeleton in one step. After high-temperature pyrolysis, atomically dispersed Mn sites are obtained, firmly and homogeneously anchored by the as-generated N-doped carbon support. The as obtained catalyst can act as cocatalyst to realize photocatalytic CO₂ reduction to produce synthesis gas under visible light using [Ru(bpy)₃]Cl₂ (bpy: 2,2′-bipyridine) as photosensitizer and triethanolamine as sacrifacial agent, with gas evolution rate of CO 1470 μmol/h/g, H₂ 1310 μmol/h/g and tunable CO/H₂ ratio from 1.12 to 0.43. Our approach is versatile to prepare a variety of morphology-controllable single atom catalysts from metal oxides for important industrial applications.