Facile synthesis and characterisation of nanosized ZnO modified with Ag2S for visible-light-induced phenol degradation

Abstract

This study investigates the synthesis, characterisation, and application of a visible-light activated binary nanocomposite catalyst for the degradation of phenol in water. Zinc oxide with a wide direct band gap (3.4 eV) is efficient under ultraviolet irradiation but shows less activity under visible light. Therefore, a sol-gel method was applied to modify it using silver sulphide whose band gap is much lower (1.1 eV) to shift the photosensitivity of the composite catalyst towards the visible light spectrum. The synthesised nanoparticles were characterised using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction which confirmed the purity of the synthesised material. At a catalyst loading of 1 gL-1, results showed that under visible light, the binary composite Ag2S/ZnO exhibited the highest phenol degradation efficiency of 50 % which was greater than ZnO that recorded a 16 % removal after 210 minutes of irradiation. These results support further development and application of visible-light-induced catalysts for photocatalytic degradation.