An Efficient Intercalation Supramolecular Structure for Photocatalytic CO2 Reduction to Ethylene Under Visible Light

Photocatalytic CO2 reduction (CO2PR) into multi-carbon products (especially C2H4) is a highly attractive route for global carbon cycle, however, which is seriously limited by sluggish C-C coupling kinetics and competitive hydrogen evolution reaction (HER) and so on. Herein, the fabrication of a novel supramolecular assembly of NiAl-Fe-TCPP is reported by intercalating iron porphyrin (Fe-TCPP) into NiAl-layered double hydroxide (NiAl-LDH), and the resultant NiAl-Fe-TCPP exhibit superior catalytic performance on CO2PR to C2H4 under visible light irradiation in presence of photosensitizer. A high C2H4 selectivity up to 93.4% in the carbon-containing products with the production rate as high as 24.7 & mu;mol h(-1) can be achieved over NiAl-Fe-TCPP. The ex/in situ X-ray absorption spectoscopy (XAS) indicates that the electron transfer between NiAl-LDH and Fe-TCPP can promote the generation of low-valence of Fe sites, resulting in the efficient production of C2H4. The spin-polarized density functional theory (DFT) calculations find that the synergistic mechanism that CO2 molecules are activated to CO on NiAl-LDH and then spilled to Fe-TCPP and coupled to COCHO#, which is further reduced to C2H4, are feasible in the perspective of Gibbs free energy. Moreover, the strong host-guest interactions between NiAl-LDH and Fe-TCPP lead to the promoted photocatalytic activity and superior cycle stability.