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

Abstract

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 MnOx 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 MnOx effectively promotes the charge separation of photogenerated carriers in TiO2(B), even better than MnOx nanoparticles-loaded TiO2(B). EPR and in-situ FTIR analyses illustrate that atomically dispersed MnOx-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.