Abstract
Pure ZnO and Ag–ZnO nanocomposites were fabricated via a sol–gel route, and the obtained photocatalysts were characterized by XRD, SEM, TEM, BET, XPS, PL and DRS. The results showed that Ag0 nanoparticles deposit on the ZnO surface and Ag modification has negligible impact on the crystal structure, surface hydroxyl group content and surface area of ZnO. However, the recombination of photogenerated electrons and holes was suppressed effectively by Ag loading. The photocatalytic activity was investigated by evaluating the degradation of MB under xenon lamp irradiation as the UV-visible light source, and the results show that the photocatalytic activity of ZnO significantly improved after Ag modification. Ag–ZnO photocatalysts exhibit higher photocatalytic activity than commercial photocatalyst P25. The degradation degree of MB for 1%Ag–ZnO was 97.1% after 15 min. ˙O2− radicals are the main active species responsible for the photodegradation process, and Ag–ZnO heterojunctions generate more ˙O2− radicals, which is the primary reason for the improved photocatalytic performance.
Highlights
Metal oxide semiconductors have been regarded as a kind of promising materials to deal with pollution due to their photocatalytic activity
Since BQ, IPA and ammonium oxalate (AO) were selected to quench cO2À, cOH and h+, respectively, the results indicate that the cO2À radical is the predominant active species in the photodegradation process. cOH and h+ species are the secondary factors
Pure ZnO and Ag–ZnO heterojunctions were synthesized via a sol–gel pathway and the photocatalytic performances were studied
Summary
Metal oxide semiconductors have been regarded as a kind of promising materials to deal with pollution due to their photocatalytic activity. ZnO, an important semiconductor material, has attracted an extensive range of research attention because of its low cost, excellent electrochemical stability and high electron mobility.[1,2,3,4] there are some defects in ZnO. It is usually active in the presence of UV light and the photoexcited electrons and holes recombine which results in a decrease of its photocatalytic property.[5,6,7,8,9,10] advancing the photocatalytic activity of ZnO has become an active research topic at present. Ion doping does not necessarily improve the photocatalytic performance of ZnO, and it has been reported that Fe–doped ZnO and Cu-doped ZnO show less photocatalytic activity than pure ZnO.[17,18]
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