Exploiting the potential of silver oxo-salts with graphitic carbon nitride/fibrous silica-titania in designing a new dual Z-scheme photocatalyst for photodegradation of 2-chlorophenol

Abstract

The series of silver oxo-salts (SO) (silver sulphate, Ag2SO4 (AS); silver phosphate, Ag3PO4 (AP); and silver carbonate, Ag2CO3 (AC)) were successfully hybridised with fibrous silica-titania (FST), and graphitic carbon nitride, g-C3N4 (CN) using the solid-state method which undergoes microwave irradiation. The physicochemical properties of prepared photocatalysts were scrutinised using Ultraviolet–visible Diffuse Reflectance Spectra (UV–Vis DRS), Photoluminescence (PL), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Electrochemical impedance spectra (EIS), Transmission electron microscope (TEM), Field-Emission Scanning Electron Microscopy (FESEM), and Fourier Transform Infrared (FTIR), while their performances were investigated on the photodegradation of 2-chlorophenol (2-CP) under visible light irradiation. The result shows that the presence of Ag2SO4 loaded on CNFST (AS-CNFST) photocatalyst possessed the best photocatalytic activity with 98% of 10 mg L-1 2-CP under visible light irradiation. The enhanced photocatalytic performance could be attributed to the strong interaction of Ag2SO4 with CNFST along with the good distribution elements of Ag and S, which contributed to the formation of oxygen vacancies and an appropriate bandgap. This gives an advantage for AS-CNFST to supreme the photocatalytic performance. Moreover, the low negative VB energy level of Ag2SO4, among other silver oxo-salt-based photocatalysts, endows the photogenerated h+ to generate more •OH with a strong oxidising ability. The presence of Ag2SO4 in CNFST benefits the construction of a dual Z-scheme mechanism that can provide the strongest redox ability in water remediation.