Construction of g-C3N4/WO3/MoS2 ternary nanocomposite with enhanced charge separation and collection for efficient wastewater treatment under visible light.

Graphitic carbon nitride (g-C 3 N 4) has enormous potentials for photocatalysis, yet it only possesses moderate activity because of excitonic effects and sluggish charge transfer. Here, we develop a novel two-dimensional g-C 3 N 4 /WO 3 /MoS 2 (CWM) ternary nanocomposite through a facile co-calcination and a hydrothermal process to reach a highly-efficient photocatalyst for organic pollutant elimination under visible light. The WO 3 and MoS 2 nanoparticles were dispersed on the ultra-thin g-C 3 N 4 nanosheets, in which the electronegative g-C 3 N 4 facilitates formation of oxygen vacancies in WO 3. Compared to pure g-C 3 N 4 , WO 3 , and binary composites, CWM exhibited higher photocatalytic activities for various organic pollutants removal under visible light irradiation. For instance, the CWM showed a removal ratio of ∼99% for RhB after only 10 min irradiation of visible light (λ > 420 nm) and nearly 100% for ciprofloxacin after 2 h of operation. The results showed that OH radicals are the main active species for organic degradation, which suggests a direct Z-scheme heterojunction in CWM that improved spatial separation of charge carries. Furthermore, the collection of electrons is significantly enhanced by MoS 2 for oxygen reduction reaction, and the increased oxygen vacancies of WO 3 further enhanced the separation of electron-hole pairs; therefore, it led to an effective suppression of charge carriers recombination. The above synergistic effects of ternary photocatalyst result in higher photocatalytic oxidation performance for wastewater treatment compared with pure WO 3 , g-C 3 N 4 and their binary composites. Efficiently improved organics and dyes degradation system is acquired using a 2-D g-C 3 N 4 /WO 3 /MoS 2 ternary nanocomposite which has improved spatial separation of charge carries and facilitated collection of electrons under visible light. Image 1 • 2-D CWM was constructed through a facile co-calcination and a hydrothermal process. • Electronegative g-C 3 N 4 facilitates the formation of oxygen vacancies in WO 3. • High rates of degradation are obtained for various organic contaminants under visible light. • The CWM shows Z-scheme heterostructure in photogenerated charges separation. • MoS 2 further hinders the charge recombination by consuming electrons for ORR. [ABSTRACT FROM AUTHOR]