, Tokyo, Japan). The crystalline structure was characterized by X-ray diffraction (XRD) analysis on a Rigaku D/max-ga X-ray diffractometer (Rigaku Corporation, Tokyo, Japan) at 40 kV with Cu Kα radiation (λ = 0.1542 nm). For the photocatalytic degradation of R6G, the photocatalysts (1.25 cm × 1.25 cm, ZnO, ZnO-H, ZnO-A, ZnO@Ag, ZnO-H@Ag, or ZnO-A@Ag) were placed into 5 ml of R6G CH5424802 price solution, allowed to equilibrate for 30 min in the darkness,

and then followed by the lamp’s (200 W, λ > 400 nm, manufactured by Oriel Instruments Corporation, Stratford, CT, USA) switching up to initiate the reaction. During the reaction, a certain amount of solution was withdrawn at certain reaction intervals to determine the remaining concentration of R6G by a JASCO model V-570 ultraviolet–visible near-infrared (UV/VIS/NIR) spectrophotometer (JASCO Analytical Instruments, Easton, MD, USA) at 527 nm. For the study on the SERS property, the substrates (ZnO, ZnO-H, ZnO@Ag, ZnO-H@Ag, and ZnO-A@Ag) were immersed in the 40 ml of R6G solutions with different concentrations for 40 min and were then analyzed by the micro-Raman spectrometer (Scinco, 532 nm; Scinco Co., Ltd. Kangnam-Gu, Seoul, South

Korea) to get the SERS spectra of R6G. Results and discussion Figure 1a,b,c shows the cross-sectional scanning electron microscopy (SEM) images of ZnO, ZnO-H, and ZnO-A. It was obvious that they have all grown perpendicular to the glass substrate and revealed that the heat treatment in Ar/H2(97/3) or air atmosphere did not Midostaurin significantly change or destroy the one-dimensional structure of ZnO nanorod arrays. From the EDX analysis, the atomic percentages of oxygen in the ZnO, ZnO-H, and ZnO-A were determined to be 52.9, 51.6, and 56.5, respectively. This revealed that the heat treatment in Ar/H2(97/3) slightly resulted in the increase

of oxygen vacancy while that in air atmosphere led to the decrease of oxygen vacancy. much Although the atomic percentages of oxygen in ZnO, ZnO-H, and ZnO-A acquired by EDX were semi-quantitative, they at least could reflect the variations of oxygen atomic percentages in ZnO, ZnO-A, and ZnO-H. The variations were reasonable based on the principle of heat treatment. As for the result that the atomic percentages of oxygen were larger than zinc in all the three ZnO nanorods, this phenomenon was similar to some works on the doped or undoped ZnO [50, 51]. Furthermore, the XRD patterns of ZnO, ZnO-H, and ZnO-A as shown in Figure 1d indicated that they all exhibited the strong characteristic peak for the (002) plane of wurtzite-type ZnO (hexagonal) around the scattering angle of 35°, revealing the heat treatment in Ar/H2(97/3) or air atmosphere did not significantly change the crystalline structure of ZnO. In addition, the absorption spectra were shown in Figure 1e. They all had no significant absorption in the visible light region.