Solar-driven photocatalysis using a new ternary g-C₃N₄/AgCl/FeOCl heterojunction: Synthesis, characterization, and...

Iron oxychloride (FeOCl) semiconductors have gained increasing interest as a potential photocatalyst due to its attractive characteristics such as narrow bandgap, simple synthesis, and low photocorrosion. However, its photocatalytic application is limited by the rapid recombination of the electron-hole pair, which compromises the material's photocatalytic efficiency. In this context, a new ternary heterojunction g-C₃N₄/AgCl/FeOCl (AFxCN) was developed using a combined calcination and coprecipitation method to achieve suppression of the recombination rate of photogenerated carriers, improving photocatalytic efficiency against organic pollutants. Structural characterization and morphological confirmed the successful heterojunction formation. Optical studies demonstrated bandgap widening, favorable for separating photogenerated charges. The efficiency of this separation was confirmed by photoluminescence (PL) analysis, photocurrent, and electrochemical impedance spectroscopy (EIS) for the AF75CN heterojunction. Under solar irradiation, this heterostructure exhibited remarkable photocatalytic activity, degrading more than 70 % of various contaminants (Malachite Green, Rhodamine B, Methyl Orange, Levofloxacin, and Phenol) in just 30 min. Photostability tests over five reuse cycles attested to the photocatalytic stability of the heterojunction. XRD analyses after the fifth cycle revealed the formation of metallic Ag, indicating the transformation of g-C₃N₄/AgCl/FeOCl to g-C₃N₄/Ag@AgCl/FeOCl after solar irradiation. The proposed photocatalytic mechanism suggests a type-I/S-scheme conjugated heterojunction for g-C₃N₄/Ag@AgCl/FeOCl.