Transition metal-promoted Fe-based catalysts for photothermal catalytic CO2 hydrogenation

Transition metals doping for Fe-based catalysts has been demonstrated in promoting the activity and regulating the selectivity in both reverse water gas shift reaction and Fischer-Tropsch synthesis. However, there are few studies that concern their catalytic performances tailored by these promoters under photothermal conditions. In this study, a series of typical MFeOx (M = Mn, Co, Cu, Zn) catalysts were synthesized with a facile co-precipitation method and their photothermal CO2 hydrogenation properties were evaluated. The results showed that the doping of Co, Cu, and Zn enhanced the activity and regulated the selectivity of Fe-based catalysts, e.g., CoFe achieving a C2+ yield of 1.73 mmol·h-1·g-1 while ZnFe almost doubling the CO2 conversion under irradiations. Mechanistic studies suggest that Co and Cu facilitated the reduction of Fe species, resulting in favorable CO2 and H2 activation. At last, a light-induced direct CO2 dissociation pathway was proposed with in situ EPR and DRIFTS characterization and analysis of the undoped Fe and ZnFe catalyst. This study provides a novel perspective on transition metal promoters for photothermal CO2 hydrogenation over Fe-based catalysts.