S-Scheme/Type-1 heterostructure stimulated WO3/g-C3N4-WS2 ternary photocatalyst with improved charge transfer mechanism for full solar spectrum photocatalysis

Abstract

Combination of liquid ultrasonication and facile hydrothermal approach were used for synthesis of novel highly efficient WO3/g-C3N4-WS2 ternary photocatalyst. The presence of noble metal free WS2 as cocatalyst induced localized surface plasma resonance (LSPR) and extended the light utilizing spectrum of the ternary composite towards the NIR. An electrochemical property reveals that it follows combined S-Scheme/Type-1 mode of changer transfer mechanism in the ternary. Transient photocurrent validated the excitation of charge carriers in the presence of light with 18.18% increases in photocurrent for ternary. Formation of internal electric field at the interface of heterojunction restricted the recombination rate. The reduction in the charge transfer resistance by the introduction of WS2 was established through LSPR effect. Pore size varies from 2 to 30 nm confirms mesoporous structure. Highest donor density of 4.24 × 1023 was found in WOCNS. This has significantly enhanced photocatalysing ability and established successful degradation of both MB and MO under the direct sunlight and artificial NIR light source. AQY of WOCNS composite was found to be 66.67% higher than pristine g-C3N4 in the NIR region. The dominance of reactive oxygen species (ROS) such as superoxide radicals (.O2-) and holes (h+) were primarily responsible for decomposition of MB and MO. The ternary exhibited high stability and reusability with a removal efficiency of 87% for up to 5th consecutive cycles. This study demonstrates the novel S-scheme/Type-1 strategy for harnessing full solar spectrum with application towards water purification and industrial wastewater treatment.