In Situ Probes into the Structural Changes and Active State Evolution of a Highly Selective Iron-Based CO2 Reduction Photocatalyst

Harnessing solar energy for CO2 2 conversion to fuels presents a sustainable alternative to fossil fuels. However, finding an economical, stable, non-toxic nanomaterial catalyst poses a significant challenge. Understanding the catalyst's active state is vital for optimal performance due to potential structural changes during reactions. Herein, we employ various in situ characterizations to detail 8-FeO OH's structural evolution during hydrogen activation, identifying its active phase while catalyzing the heterogeneous reduction of CO2 2 by H2. 2 . Using in situ environmental transmission electron microscopy, 8-FeOOH is first dehydrated to a-Fe 2 O 3 , then reduced to Fe3O4, 3 O 4 , and finally to a-Fe. Other in situ characterizations revealed that the active state of the catalyst (Fe-350-H2) 2 ) is a mixture of Fe3O4 3 O 4 and a-Fe. A detailed investigation into the photocatalytic CO2 2 reduction using batch, flow, and LED reactors unveiled that the Fe-350-H2 2 catalyst exhibits superior activity and selectivity in activating the reverse water gas shift reaction compared with similar iron-based catalysts.