Synthesis of CdS–SnS photocatalyst by chemical co-precipitation for photocatalytic degradation of methylene blue and rhodamine B under irradiation by visible light

Abstract

The development of photocatalysts for use in degrading hazardous dyes has attracted significant attention. In this study, a CdS–SnS heterostructure was synthesized to promote the photocatalytic activity of visible light-driven pure CdS. The diffuse reflectance and photoluminescence spectra indicated a narrow band gap (2.04 eV) and the fast transfer and separation of charges in CdS–SnS (Sn/Cd = 1). Electrochemical impedance spectroscopy demonstrated that the transfer of charge carriers was accelerated more in CdS–SnS (Sn/Cd = 1) (Z′ = 13 kΩ) than CdS–SnS (Sn/Cd = 1/3) (Z′ = 15 kΩ) and CdS (Z′ = 50 kΩ). The ultraviolet–visible absorption spectra showed that the photodegradation of methylene blue (MB) improved from 80% with CdS to 92% and 99% using CdS–SnS with Sn/Cd = 1/3 and 1, respectively. The photodegradation of rhodamine B (RhB) improved from 67% with CdS to 95% and 99% using CdS–SnS with Sn/Cd = 1/3 and 1, respectively. The effects of various parameters on photodegradation were also investigated. This study investigated the performance of CdS–SnS in the photodegradation of MB, RhB, and phenol for the first time. The photodegradation and absorption kinetics were described via pseudo-first order and pseudo-second order kinetics to obtain adsorption capacities for CdS–SnS (Sn/Cd = 1) of 35.84 and 26.88 mg/g in MB and RhB solutions, respectively.