Highly Enhanced Photocatalytic NO Removal and Inhibited Peroxyacetyl Nitrate Formation in Synergistic Acetaldehyde Degradation

The coexistence of NO and CH₃CHO in the air is considered to produce secondary peroxyacetyl nitrate (PAN) under sunlight irradiation, threatening the ecological environment and public health. Herein, we provide a simple strategy for the photocatalytic removal of NO and acetaldehyde (CH₃CHO) on Sr₂Sb₂O₇. In comparison with the single removal, the nearly complete removal of NO is reached by deep oxidation to NO₃^- with the assistance of CH₃CHO. The underlying mechanism is revealed by GC-MS, in situ DRIFTS, and density functional theory calculations. The intermediates ^•CH₃ from CH₃CHO and NO₂^- from NO tend to bond and further oxidize to CH₃ONO₂, thus promoting NO removal. CH₃NO₂ and CH₃ONO₂ are the key products instead of PAN on Sr₂Sb₂O₇ from the synergistic degradation of NO and CH₃CHO. This work brings new insights into reaction pathway regulation for promoting performance and suppressing byproducts during synergistic air pollutant removal.