2D Layered g-C₃N₄/WO₃/WS₂ S-Scheme Heterojunctions with Enhanced Photochemical Performance

Abstract

Graphitic carbon nitride (g-C3N4)/WO3/WS2 ternary heterojunctions were fabricated for the first time via in situ growing WO3 and WS2 on superior thin g-C3N4 nanosheets. A mechanic chemical prereaction plays an important role in the formation of S-scheme heterojunctions. Namely, the heterostructured photocatalyst prepared by optimized preparation conditions revealed enhanced photodegrading activity (∼8.6 times of pure g-C3N4) for organic pollutants in the visible light region. Compared with g-C3N4 nanosheets, the rate of hydrogen generation increased to ∼7.8 times higher, in which the apparent quantum efficiency at 420 nm reached 8.9%. Particularly, the as-prepared ternary photocatalyst exhibited a hydrogen generation rate of 29 μmol g–1 h–1 even without Pt loaded. The matched energy band structure, band bending effect, and intimate interface contact of the 2D/2D g-C3N4/WO3 heterojunction together determined the S-scheme electron transfer path. Photogenerated electrons and holes with high redox capacities were reserved to participate in the photocatalytic process. In addition, the oxygen vacancies and WS2 improved light response and further promoted the separation of charge carriers. This result offered a new idea for the construction of metal-free photocatalysts to be applied in the photochemistry field.