To compare the durability of TNT an

To compare the durability of TNT and 001-TNT, five successive cycles of photocatalytic degradation of toluene were conducted. The deactivation of TiO 2 photocatalyst duringtoluene degradation has been frequently reported in the literature. 56 The color of TiO 2 was changed from white to brown when the catalyst deactivation was observed as a result of the surface accumulation of carbonaceous intermediates. These are more strongly adsorbed on the TiO 2 surface than the parent toluene molecules. 9,57 Our previous study observed that TNT exhibited a markedly higher resistance against the photocatalyst deactivation compared to TiO 2 nanoparticulate film due to the presence of open channels which facilitates the mass diffusion of VOCs and O 2 molecules onto active sites of photocatalysts. 16,17 Nevertheless, TNT exhibited a gradual deactivation with repeated cycles of photocatalytic degradationof toluene. However, 001-TNT maintained its photocatalytic activity during five cycles without showing any sign of deactivation (Figure 5b). Even if 001-TNT was deactivated after the photocatalytic degradation of higher concentration of toluene, its photocatalytic activity could be regenerated by UV irradiation in the clean air. With a combination of morphologycontrol (open channel structure) and facet engineering, 001-TNT could be developed as an efficient and durable photocatalyst for air purification.