Finally, drawing on this knowledge, we hypothesized that the superior oxygen reduction kinetics at TiO2 modified with vanadate SACs might be highly beneficial also for other photocatalytic transformations beyond oxidative degradations of organic pollutants in aqueous solutions. To this end, we tested the activity and selectivity of a-TiO2(400)-V SA in gas phase photocatalytic conversion of NO2 (for details see Supporting Information, Section 1.5 and Figure ). Indeed, the overall activity in the conversion of NO2 was enhanced by the factor of ~3 at a-TiO2(400)-V SA as compared to pristine a-TiO2(400) (Table ), which can be again ascribed to effective de-bottlenecking of the oxygen reduction pathway. Moreover, the vanadate SACs change partially the selectivity of the process, as a portion of NO2 (~33%) is reduced to NO, a process that does not occur in unmodified TiO2, where all NO2 is converted to nitrate. These results suggest that, though nitrate is still the dominant product, part of the photogenerated electrons trapped at reduced V(IV) sites reacts directly with NO2 to produce NO, most likely via nitrite intermediate. These results confirm that the highly beneficial role of vanadate SACs at TiO2 for photoactivity enhancement is not confined to photodegradation of organic compounds, but represents a rather general feature that can be utilized in any photocatalytic conversion that relies on rapid turnover of electron acceptors that react readily with reduced vanadate SACs.