Surface-oxygen-vacancy-promoted Z-scheme CeO2-AgI heterostructured photocatalysts were successfully fabricated via a hydrothermal route combined with a precipitation process. Surface oxygen vacancies were formed on the synthesized CeO2-AgI photocatalyst, as determined by X-ray photoelectron spectroscopy. These oxygen vacancies could extend the lifetime of the charge carriers and enhance the photocatalytic activity of these catalysts for rhodamine B (RhB) dye degradation. Among the as-synthesized photocatalysts, the 20 wt% CeO2-AgI (CA-2) nanocomposite demonstrated the highest photocatalytic activity towards the degradation of RhB with 3.28- and 29.8-fold higher activity than pure AgI and CeO2 nanostructures, respectively. In addition, to ensure the visible light photocatalytic activity of the CeO2-AgI nanocomposite, decomposition studies were performed using a colorless substrate such as phenol. The mechanism for the enhanced photocatalytic performance of the CeO2-AgI photocatalyst is proposed to be based on efficient separation of photogenerated electron-hole pairs through a Z-scheme system, in which oxygen vacancy states promote charge separation. Experiments using scavengers of reactive species combined with photoluminescence analysis provide significant evidence for the oxygen-vacancy-mediated Z-scheme mechanism of the photocatalyst. Moreover, the as-prepared oxygen-deficient CeO2-AgI photocatalysts exhibited excellent cycling stability.
Bibliographical noteFunding Information:
This work was financially supported by National Research Foundation of Korea (NRF) grants funded by the Korean government (MEST and MSIP) (2007-0056095, 2013S1A2A2035406, 2013R1A1A2009575, and 2014R1A4A1001690). This research has been supported in part by Global Research Laboratory Program [Grant No. 2009-00439] and by Max Planck POSTECH/KOREA Research Initiative Program [Grant No. 2011-0031558] through the National Research Foundation of Korea (NRF) funded by Ministry of Science, ICT and Future Planning.
© The Royal Society of Chemistry 2016.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)