Facile Synthesis of CeO2 Nanosheets Decorated upon BiOI Microplate: A Surface Oxygen Vacancy Promoted Z-Scheme-Based 2D-2D Nanocomposite Photocatalyst with Enhanced Photocatalytic Activity

Construction of a visible light driven Z-scheme based photocatalytic system is a hot topic of research because of the potential to alleviate both energy and environmental issues. In the present study a series of surface vacancy mediated BiOI-CeO2 nanocomposites were prepared and their crystallographic, morphological, optical, and electrochemical behavior were characterized through XRD, TEM, FESEM, UV-vis DRS, PL, ESI, and Mott-Schottky techniques. From the XPS analysis, it could be said that a high amount of oxygen defects and metallic bismuth were present on the composite than neat CeO2 which was the major cause of enhancement in the photocatalytic activity. Further the photocatalytic efficiency of the as prepared samples was tested toward RhB decolorization/phenol oxidation as well as for O-2 gas evolution. It was observed that 40 wt % BiOI-CeO2 nanocomposite exhibited highest photocatalytic activity among neat and other composites, i.e., 89% decolorization of 100 ppm RhB and produces 323 mu mol/2h of O-2 under visible light illumination. To justify the enhanced photocatalytic activity of the material a Z-scheme-based charge transfer mechanism was proposed. Where surface oxygen vacancy exists on CeO2, I-3(-)/I- reversibility pair through Bi metal on BiOI, scavenger experiment, PL spectra, and Nyquist plot provide solid evidence toward a Z-scheme charge transfer pathway. This work will provide some useful information in course of developing of Z-scheme-based photocatalyst without an external mediator.