The photoinduced holes (trapped by H2O) produce hydroxyl radical species (·OH) and the photoinduced electrons (trapped by O2 and H2O) produce hydroxyl radical

species (·OH), which are extremely strong oxidants for the HTS assay degradation of organic chemicals (Equations 4 and 5) [24]. It is known that ZnO is an n-type semiconductor while Ag2O is a p-type semiconductor. Thus, the Fermi levels of both n-type and p-type tend to obtain equilibrium, resulting in the energy bands of ZnO downward with the upward shifts of the Ag2O band. Moreover, click here there will be an inner electric field in the interface between ZnO and Ag2O in the composite, leading to a positive charge in the ZnO region and a negative charge in the Ag2O part.

After the illumination of UV light, the photoinduced electrons and holes are created in the composite and subsequently transferred by the drive of inner field. Photoinduced electrons in the CB of Ag2O would move to the positively charged ZnO, while the holes of ZnO will be transferred to the negatively charged Ag2O part by the potential energy. Hence, the photoinduced electrons and holes could be effectively separated through charge transfer process at the interface of the two semiconductors, and the photocatalytic process can be described as follows: (2) (3) (4) (5) Figure 6 Schematic diagram of electron–hole separations at the interface and in both semiconductors. The results in this paper show that ZnO-Ag2O composites have higher photocatalytic activities than pure ZnO and pure Ag2O, which is mostly attributed to the inner electric field introduced LXH254 in vivo by the n-type ZnO and p-type Ag2O effectively separating the photoinduced electrons and holes. Conclusions Flower-like ZnO-Ag2O composites were prepared by a chemical co-precipitating method. The XRD profiles confirm that the composite is composed of cubic-phase Ag2O and wurtzite-phase ZnO. Ag2O particles decorated on ZnO composite flowers Nintedanib nmr show higher photocatalytic activity than pure components under UV irradiation for the degradation of MO. The activity dependence on the component

reveals that the increased Ag2O deposited on the composite greatly enhanced the photocatalytic activity, which can be attributed to the p-n junction in the composite effectively inhibiting the recombination of electron–hole pairs. Acknowledgements This work was supported by a fund from Heilongjiang Provincial Committee of Education (12511164). References 1. Fujishima A, Honda K: Electrochemical photolysis of water at a semiconductor. Nature 1972, 238:37–38.CrossRef 2. Hoffmann MR, Martin ST, Choi W, Bahnemann DW: Environmental applications of semiconductor photocatalysis. Chem Rev 1995, 95:69–96.CrossRef 3. Duan XW, Wang GZ, Wang HQ, Wang YQ, Shen C, Cai WP: Orientable pore-size-distribution of ZnO nanostructures and their superior photocatalytic activity. CrystEngComm 2010, 12:2821–2825.CrossRef 4.