Suitable energy avenue for the dimension-matched cascade charge transfer mechanism in a g-C3N4/TS-1 heterostructure co-doped with Au–TiO2 for artificial photosynthetic green fuel production

Abstract

Ultrathin electron-modulated porous zeolite MFI hollow sulfated doped Ti-containing molecular sieves (TS) were modified through a process that included the incorporation of sulfur and g-C₃N₄ nanosheets, followed by the integration of Au-modified TiO₂ with an appropriate energy platform. The resulting hybrid material exhibited remarkable visible-light photoactivities, showing ≈18 and 19 times higher efficiency in producing H₂ and CH₄ from water and CO₂, respectively, compared to the pristine zeolite TS. Notably, the hybrid material demonstrated excellent quantum efficiencies at a wavelength of 420 nm. The observed phenomenon is directly linked to the effective band gap engineering achieved through the cooperative effect of g-C₃N₄ in the nanocomposite. This engineering approach enhances both light capture and charge separation processes. Various spectroscopic techniques and electrochemical studies confirm that the distinct photoresponses can be attributed to the nanocomposite's remarkable surface area, resulting from its permeable morphology. Moreover, the modulation of excited electrons from TS nanosheets to g-C₃N₄, along with the catalytic functions of decorated sulphur and coupled Au–TiO₂ nanosheets, significantly contributes to improved charge separation. Through conversion experiments utilizing ¹³CO₂ and D₂O, it was determined that ˙CO₂ and ˙H are the active species responsible for the production of CH₄ from CO₂. This research opens up possibilities for the development of highly efficient and stable nanophotocatalysts, enabling latent energy production and environmental remediation.