Improvement in visible-light-induced photocatalytic activity of Ag–CeO2 Schottky-type contact heterostructures

Abstract

This study has widely described the fabrication and performance of a series of Ag–CeO2 Schottky plasmonic photocatalysts under visible light irradiation. A conventional wetness incipient impregnation technique has been utilized to load Ag metal on the surface of CeO2 nanoparticles synthesized by the hydrothermal method. The as-synthesized photocatalysts have been identified using combined characterizations of XRD, FTIR, FESEM, EDS, TEM and UV–Vis DRS. The photocatalytic activity of as-synthesized samples has been investigated in terms of degradation efficiency of methylene blue (MB) as a function of involved operating factors including irradiation photon energy, irradiation time, pH, initial MB concentration, photocatalyst dose and amount of loaded Ag. All of the Ag–CeO2 samples have exhibited higher photocatalytic efficiencies than pure CeO2 with the order of 8%-Ag–CeO2 > 5%-Ag–CeO2 > 2%-Ag–CeO2 > pure CeO2. The enhanced photocatalytic activity has been ascribed to the improved light absorption toward visible irradiation photons due to the surface plasmon resonance, supported by the DRS results. A Schottky scheme photocatalytic mechanism that highlights charge transfer pattern has been developed for photodegradation rate. Photocatalytic process kinetics has been found to obey the pseudo-first-order expression according to the Langmuir–Hinshelwood model.