The blank experiment result is also shown. Generally, h+, SB525334 research buy ·OH, ·O2, and H2O2 are thought to be the main active species responsible for the dye degradation . It is known that ethanol is a scavenger for · OH, and KI is a scavenger for both · OH and h+ [32, 33]. By investigating the effect of ethanol and KI on the photocatalytic efficiency of the composites toward the AO7 degradation, we can clarify the role of h+ and · OH in the photocatalysis. The role of · O2 and H2O2, which are derived from the reaction between dissolved O2 and photogenerated e-, on the dye degradation can be examined by investigating the effect of N2 on the photocatalytic
efficiency since the dissolved O2 can be removed from the solution by the N2-purging procedure. Figure 8 shows the effect of N2 (bubbled at a rate of 0.1 L min-1), ethanol (10% by volume), and KI (2 × 10-3 mol L-1) on the degradation percentage of AO7 after 6 h of photocatalysis. It is demonstrated that when adding ethanol to the reaction solution, the photocatalytic degradation
of AO7 undergoes a substantial decrease, from approximately 88% under normal condition to approximately 40% on addition of ethanol. This suggests that · OH radical is an important active species responsible for the dye degradation. Figure 7 provides direct evidence showing the generation of · OH radicals over the irradiated SrTiO3-graphene composites. The addition of KI to the reaction solution results in a higher suppression of the photocatalytic efficiency compared to the addition NVP-HSP990 clinical trial of ethanol, where only 16% of AO7 is caused to be degraded, indicating that the photogenerated h+ also plays a role in the degradation of AO7. Idoxuridine In addition, the photocatalytic efficiency decreases slightly under N2-purging condition, implying
comparatively minor role of · O2 and/or H2O2 for the dye degradation. Figure 8 Effects of N 2 , ethanol, and KI on the degradation percentage of AO7 over SrTiO 3 -graphene(7.5%) composites. The irradiation time is 6 h. In order to understand the photocatalytic mechanism of semiconductor-based photocatalysts, it is essential to determine their energy-band potentials since the redox ability of photogenerated carriers is associated with energy-band potentials of photocatalysts. The conduction band and valence band potentials of SrTiO3 can be calculated using the following ARRY-438162 cost relation : (1) where X is the absolute electronegativity of SrTiO3 (defined as the arithmetic mean of the electron affinity and the first ionization of the constituent atoms) and estimated to be 5.34 eV according to the data reported in the literature [35, 36], E e is the energy of free electrons on the hydrogen scale (4.5 eV), and E g is the bandgap energy of SrTiO3 (3.35 eV). The conduction band and valence band potentials of SrTiO3 vs. normal hydrogen electrode (NHE) are therefore calculated to be E CB = -0.84 V and E VB = +2.51 V, respectively.