Enhanced photocatalytic degradation of 2-chlorophenol over Z-scheme heterojunction of CdS-decorated oxygen-doped g-C3N4 under visible-light

Constructing photocatalysts with outstanding visible light utilization efficiency and a high-efficiency photo-generated charge transfer rate is the key to the photodegradation of organic pollutants in wastewater. Oxygen-doped graphitic carbon nitride (g-C3N4) responsive to a broad visible light range was prepared, to which CdS nanoparticles (NPs) were anchored to fabricate a Z-scheme heterojunction, constructing abundant charge transport orbitals that facilitate interfacial photo-generated charge separation. Meanwhile, density functional theory (DFT) calculations and electron spin resonance (ESR) tests proved that oxygen-doped g-C3N4/CdS-3 (O-CN/CdS-3) followed the Z-scheme charge transfer mechanism. The results showed that O-CN/CdS-3 degraded 10 ppm of 2-chlorophenol (2-CP) within 60 min, with a degradation rate constant (k = 0.10832) of around 11.5-fold that of g-C3N4 (0.00945). Furthermore, the active species and main intermediate products were also studied to explore the possible degradation pathway of 2-CP. Overall, this strategy provides insight for constructing other Z-scheme heterojunction photocatalysts for the efficient degradation of CPs. [Display omitted] •A novel oxygen-doped g-C3N4/CdS Z-scheme heterojunction was synthesized and proved.•Z-scheme charge transfer pathway was confirmed using DFT calculations and ESR experiments.•Z-scheme system could hinder photoelectron-hole recombination and promote charge transfer.•A plausible 2-CP degradation pathway was proposed based on identified intermediates.