Photoelectrochemical performance and S-scheme mechanism of ternary GO/g-C3N4/TiO2 heterojunction photocatalyst for photocatalytic antibiosis and dye degradation under visible light

Abstract

Herein, an efficient ternary S-scheme heterojunction photocatalyst, GO/g-C3N4/TiO2, was constructed and investigated toward photocatalytic wastewater treatment. The three-step synthesis method with regulated optimal calcination temperature and g-C3N4 content was used to insert TiO2 nanoparticles into the interbedding structure of the g-C3N4 lamella and GO layer in situ, obtaining a pepperoni pizz-like nanostructure. Morphology, crystalline structures, composition and photoelectrochemical performance of samples were determined by TEM, XRD, XPS, FTIR, DRS, EIS and PL, etc. The charge transfer mechanism of GO/g-C3N4/TiO2 was investigated by employing VB-XPS, Tauc plot, EPR, and DFT. Constructing the efficient S-scheme heterojunction photocatalyst by introduction of GO as efficient photo–-electron accepter significantly promoted the photoinduced charges transferring. The adsorption edge of the GO/g-C3N4/TiO2 was dramatically extended to the 595.02 nm in visible light region by g-C3N4 participating in band rearrangement to narrow band-gap barriers to 2.55 eV. Thus, the successful construction of S-scheme charge transfer route for the ternary photocatalyst led to high visible light utilization and enhanced charge transferring ability, which were responsible for the excellent photocatalytic activity. The antibacterial rate for Escherichia coli (E. coli) could reach up to 98.18% and degradation rate for methylene blue (MB) (10 mg/L) could reach up to 98.84% under visible light.