Atomically dispersed Mn sites on TiO₂(B) microspheres enables efficient photocatalytic abatement of NOx

While photocatalytic technology has been recognized as an effective means for removing low-concentration NOx in ambient atmosphere, it still faces the challenge of the deep oxidation in high efficiency. In many cases, the release of more toxic NO₂ byproduct appeared to be inevitable during the photocatalytic oxidation of NO. Herein we report that the atomically dispersed MnO_x cocatalyst on TiO₂(B) microspheres could significantly enhance the deep oxidation of NOx under mild photocatalytic conditions (1 mW/cm² UV-A light, 1 L/min flow rate). At an initial NO concentration of 0.35 ppm, ca. 67.15% of NO is oxidized on the MT-0.5 sample, which is 2.76 times higher than the pristine TiO₂(B) sample. More importantly, the release of NO₂ is suppressed by 2.11 times. Comprehensive spectral analyses suggest that atomically dispersed MnO_x effectively promotes the charge separation of photogenerated carriers in TiO₂(B), even better than MnO_x nanoparticles-loaded TiO₂(B). EPR and in-situ FTIR analyses illustrate that atomically dispersed MnO_x-loaded TiO₂(B) sample exhibits excellent low concentration NOx abatement performance, thus providing a rational mechanism for the NO deep oxidation pathway. This study not only provides a unique approach for preparing non-noble metal atomically dispersed co-catalysts, but also affords an effective means for efficient photocatalytic NO degradation.