Efficient silver nanocluster photocatalyst for simultaneous methyl orange/4-chlorophenol oxidation and Cr(VI) reduction

Metal nanoclusters have shown great potential in photocatalysis, while simultaneous removal of both inorganic and organic contaminants by metal nanoclusters under visible light is less explored. Here, we synthesized Agm(SR)n (SR represents 3-mercaptopropyltriethoxysilane ligand) nanoclusters (similar to 1 nm) via a reduction of silver triphenylphosphine under ambient conditions in the presence of 3-mercaptopro-pyltriethoxysilane. The nanocluster was characterized by UV-vis spectroscopy, high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectrum (FTIR), and X-ray photoelectron spectroscopy (XPS). Under 5 W blue LED, the Agm(SR)n/P25 exhibits enhanced catalytic activity for simultaneous methyl orange (MO) oxidation and Cr(VI) reduction, and also for synchronous 4-chlorophenol oxidation and Cr(VI) reduction. Mechanism studies by electrochemical impedance spectroscopy (EIS), photoluminescence (PL), electron spin resonance (ESR) etc. and control experiments reveal that the unique structure of silver nanoclusters with thiolate ligands is vital to the high catalytic performance, and both the photo-generated holes and superoxide radicals are responsible for the decomposition of MO. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.