Design and construction of a double Z-scheme CdS@g-C3N4/Bi2MoO6 ternary nanocomposite: Photocatalytic degradation in visible light, adsorption and electrochemical applications

Abstract

Improved photocatalytic performances can be achieved by synthesizing double heterojunction nanocomposites with suitable conduction band (CB) and valence band (VB) edge potentials. In the current study, a hydrothermal approach was used to successfully synthesize a Z-scheme CdS@g-C3N4/Bi2MoO6 (CdS@GB) ternary nanocomposite with varied CdS contents. The photocatalytic efficiency of the as-synthesized materials was determined by studying the degradation of Rhodamine B (RhB) and Acetaminophen (ACM) pollutants. The experimental results revealed that 15 wt% CdS@GB (15CdS@GB) ternary composite showed the highest photocatalytic performance indicating 98.8 and 83% degradation of RhB and ACM in 35 and 140 min of irradiation, respectively. The stability of the ternary composite was also relatively high even after four consecutive cycles of photodegradation. The main reactive species involved in photodegradation processes was O2•- as revealed by the quenching experiments. The nitro blue tetrazolium (NBT) experiment further confirmed it, which showed the high production of O2•- in the reaction mixture. The synthesized ternary composites were used to study the dark adsorption of RhB, and the results confirmed the applicability of the Langmuir isotherm model. The electrochemical properties of the synthesized materials were investigated using electrochemical impedance spectroscopy (EIS) and cyclovoltammetry (CV). The results showed that 15CdS@GB has the lowest charge-transfer resistance and highest specific capacitance. Based on the findings, a double Z-scheme mechanism route was designed and presented to explain the photodegradation of the target pollutants.