Tailoring atomically dispersed Fe-induced oxygen vacancies for highly efficient gas-phase photocatalytic CO₂ reduction and NO removal with diminished noxious byproducts

Single-atom-supported metal oxides have attracted extensive interest in energy catalysis, offering a promising avenue for mitigating greenhouse gas emissions and environmental pollution. This study presents a facile synthesis of single-atom Fe-modified Bi₂WO₆ photocatalysts. By carefully tuning the Fe ratios, the 1.5Fe-Bi₂WO₆ sample demonstrates exceptional photocatalytic efficiency in CO₂ to CO reduction (36.78 μmol g⁻¹). Additionally, an outstanding NO removal performance is also achieved through this photocatalyst with an impressively low conversion of toxic NO₂ at just 0.37%. The reaction intermediates and mechanisms governing the photocatalytic reduction of CO₂ into CO are elucidated using in situ DRIFTS and in situ XAS techniques. Regarding NO removal, the introduction of Fe single-atoms, along with induced oxygen vacancies, plays a pivotal role in facilitating the transformation of NO and NO₂ into nitrate by stabilizing NO and NO₂ species. Mechanistic insights into photocatalytic NO oxidation are garnered through scavenger trapping and EPR experiments employing DMPO. This study emphasizes single-atom-supported metal oxide's potential in sustainable chemistry and air purification, providing a promising solution for urgent environmental challenges.