NOx (mostly NO and NO2) is emerging as one of the most serious pollutants in air pollution. Environmental nanomaterial based photocatalytic technique is known as a promising approach to reduce NO concentrations by converting it, with the assistance of solar light. Till now, little is known about specific methods and profound insights for enhancing NO conversion pathways, inhibiting by-products, e.g., NO2 and N2O, which are more toxic than NO, revealing reaction mechanisms and, improving selectivity of nontoxic product (N2 and NO3-) formations as well as quantum efficiency enhancements. In our previous study, we found that, by simply controlling the annealing temperature, both concentration and location of Ti3+ defects can be well managed in the subsurface/bulk regions of TiO2 nanocrystals. Furthermore, with a facile photochemical reduction process followed by post-annealing, we’ve studied defective Ag-TiO2−x for visible light NO conversions, in which superior efficiency and selective photo-reduction products of N2 were observed. In addition, we explored a dual defective (metal defects of Ti3+, Cu+ and oxygen vacancies) octahedron shaped perovskite CaCu3Ti4O12 with codominant ({001} and {111}) exposed facets, which showed fascinating visible light photoactivity. Recently, we’ve developed serious of defective perovskites and g-C3N4 and reveled relatively higher NO conversion effectiveness to generate NO3− by producing photocatalytically active species of H2O2, predominant carrier separation, as well as higher selectivity to produce N2 by inhibiting byproduct generations. Excitingly, we found that various defects such as oxygen vacancies and carbon defects could enhanced photocatalytic NO conversions and selectivity. Results showed that these defective catalysts are not only superior in visible-light photocatalytic NO conversion, and they also have great advantages in inhibiting the toxic byproduct generation, facilitating nonselective products NO3- formation and, promoting concurrent selective production of N2 and O2 originated from high abundant oxygen defects. On the bases of these systematic studies, we’ve gain profound insights for photocatalytic NO conversion process and proposed that defect manipulations in catalysts are the utmost significant in improving photocatalytic NO conversions/transformation and enhancing reaction selectivity.

Surface defect chemistry modulation in photocatalytic NO conversion: Reactivity and mechanism

2019 Fall National Meeting

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