Well-structured 2D Fe₂TiO₅ coupled Fg-C₃N₄/Ag₃VO₄ dual heterojunction for highly efficient and stable photocatalytic CO₂ conversion to methane

In this study, a ternary Fg-C₃N₄/Ag₃VO₄/Fe₂TiO₅ nanocomposite with dual heterojunctions was successfully synthesized via a facile chemical precipitation method and evaluated for its effectiveness in photocatalytic CO₂ conversion. Extensive characterization techniques, including XRD, SEM, EDS mapping, TEM, XPS, UV–Vis DRS, were applied to explore the nanocomposite’s physicochemical properties and to elucidate the reaction mechanisms. The Fg-C₃N₄/Ag₃VO₄/Fe₂TiO₅ nanocomposite exhibited a significant enhancement in CO₂ conversion performance, particularly for CH₄ production. The optimized CH₄ yield reached 528.4 μmol/g-cat, representing a 4.3-fold and 2.4-fold increase compared to pristine Fg-C₃N₄ and Ag₃VO₄₅, respectively. Moreover, the composite photocatalyst demonstrated excellent stability and recyclability, retaining its efficiency over four successive cycles. The dual heterojunctions played a crucial role in enhancing the separation of photogenerated electron–hole pairs while minimizing recombination. This work offers valuable insights into the development of advanced photocatalysts with dual heterojunctions, presenting a promising approach for the efficient production of high-value products such as CH₄.