Photothermal Conversion of CO₂ with Tunable Selectivity Using Fe-Based Catalysts: From Oxide to Carbide

Abstract

Conversion of CO2 into fuels via solar energy would be a promising strategy to reduce CO2 emissions and produce value-added carbon compounds. However, the development of efficient light-harvesting and photocatalytic systems remains a significant challenge because of scarcity of low-cost and high-efficiency catalysts in CO2 conversion. Herein, a tunable selectivity in photothermal CO2 conversion was demonstrated over a series of Fe-based catalysts developed through a simple hydrogenation/carbonization treatment with commercial Fe3O4 as a precursor. The Fe3O4 catalyst demonstrated a full selectivity toward CO (about 100%) and 11.3 mmol g–1 h–1 activity for the photothermal catalytic conversion of CO2. More importantly, the pure-phase θ-Fe3C produced remarkably high selectivity toward hydrocarbon products (>97%) and superior activity (10.9 mmol g–1 h–1) in the photothermal conversion of CO2. Meanwhile, it is found that the selectivity toward a hydrocarbon (CHx) can be modulated by the extent of hydrogenation/carbonization of the Fe3O4 precursor. In addition, we demonstrated the vital influence of the nonthermal effect on the enhanced catalytic performance with the Fe-based catalysts during the photothermal conversion of CO2.