Proton-Independent CO

CO2 and NO commonly coexist in flue gas, yet they are typically treated as independent targets in photocatalysis. Here we demonstrate that introducing NO can strongly promote photocatalytic CO2-to- CO conversion over TiO2 P25 in a batch gas-phase system. And larger NO inputs yield higher CO output per dosing event. Product analysis shows that NO is predominantly oxidized to NO2 and surface nitrate, as evidenced by flue-gas analysis and ion chromatography of catalyst eluates, whereas CO is essentially the only detectable CO2 reduction product. In situ DRIFTS further identifies the growth of nitrate/nitrite-like bands (1650–1250 cm⁻¹) during illumination under CO2 + NO. Importantly, the NO-triggered CO formation persists under anhydrous conditions, indicating that CO2-to-CO conversion can proceed without an external proton source and is inconsistent with a purely PCET-driven pathway. These results suggest an OCET-like coupling scenario in which NO oxidation provides an efficient oxidative channel, suppresses charge recombination, and enhances electron utilization for selective CO production.