Ag3PO4/carbon nanotubes/Ni film electrodes: photoelectrocatalytic properties and mechanism of rhodamine B degradation under an applied negative bias

Abstract

Ag3PO4/CNTs/Ni composite thin film electrodes were prepared using electrochemical co-deposition. The surface morphology and structural properties of the electrodes were characterized using scanning electron microscopy (SEM), X-ray diffraction, and Raman and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). SEM showed that spherical Ag3PO4 nanoparticles (average diameter of 20–30 nm) were distributed uniformly on the outermost layer of the composite film when the fabrication process was optimized. The inner layer consisted of a network structure that contained interlaced Ag3PO4 and CNTs. The photoelectrocatalytic (PEC) activity and stability of the thin films were investigated by following the degradation of rhodamine B (RhB) at a negative bias under visible light irradiation. At an optimum negative bias of − 0.10 V, the efficiency of PEC degradation of RhB was 2.74 times greater than that observed when a Ag3PO4/Ni thin film was used. Importantly, the Ag3PO4/CNTs/Ni composite films exhibited a synergistic photoelectric effect and PEC stability, and could be reused five times without any significant decrease in the catalytic activity of the film. A reaction mechanism for the PEC degradation of RhB at negative bias by the Ag3PO4/CNTs/Ni thin films was proposed.