Harnessing solar energy for CO₂ 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 δ-FeOOH’s structural evolution during hydrogen activation, identifying its active phase while catalyzing the heterogeneous reduction of CO₂ by H₂. Using in situ environmental transmission electron microscopy, δ-FeOOH is first dehydrated to α-Fe₂O₃, then reduced to Fe₃O₄, and finally to α-Fe. Other in situ characterizations revealed that the active state of the catalyst (Fe-350-H₂) is a mixture of Fe₃O₄ and α-Fe. A detailed investigation into the photocatalytic CO₂ reduction using batch, flow, and LED reactors unveiled that the Fe-350-H₂ catalyst exhibits superior activity and selectivity in activating the reverse water gas shift reaction compared with similar iron-based catalysts.

利用太阳能将CO ₂转化为燃料是化石燃料的可持续替代品。然而，寻找经济、稳定、无毒的纳米材料催化剂提出了重大挑战。由于反应过程中潜在的结构变化，了解催化剂的活性状态对于获得最佳性能至关重要。在此，我们采用各种原位表征来详细描述δ-FeOOH在氢活化过程中的结构演化，识别其活性相，同时催化H _{2催化CO 2}的非均相还原。利用原位环境透射电子显微镜，δ-FeOOH首先脱水为α-Fe ₂ O ₃，然后还原为Fe ₃ O ₄，最后还原为α-Fe。其他原位表征表明催化剂(Fe-350-H _{2 )的活性态是Fe 3} O ₄和α-Fe的混合物。使用间歇式、流动式和LED反应器对光催化CO ₂还原的详细研究表明，与类似的铁基催化剂相比，Fe-350-H ₂催化剂在激活逆水煤气变换反应方面表现出优异的活性和选择性。