Direct Z-scheme SrMoO4/g-C3N4 heterostructure with enhanced photocatalytic activity for decontamination in wastewater: UV and solar irradiation approach

Abstract

The improper dumping of organic contaminants in aquatic ecosystems has stirred interest in the search for new technologies aimed at wastewater treatment, aiming to permanently reduce the concentration of these compounds in the environment. For this purpose, SrMoO4 was used to prepare direct Z-scheme SrMoO4/xg-C3N4 heterostructures with different amounts of g-C3N4 (x = 0.3, 0.6 and 0.9 g) via co-precipitation route with additional hydrothermal treatment at 140 °C. The heterostructure properties were characterized by XRD, Raman spectroscopy, SEM-FEG, XPS, UV–vis/DRS, BET, PL, EPR and zeta potential. Photocatalytic activity was evaluated in methylene blue solution under natural sunlight and ultraviolet (UV). Heterostructures prepared with 0.9 g of g-C3N4 and processed for two hours in a hydrothermal system (SMOCN9-2h) exhibited the highest photocatalytic activity, degrading 90.70 % and 99.60 % under UV and sunlight, respectively. It is believed that the SMOCN9-2h heterostructure performed best due to increased specific surface area, decreased bandgap energy and reduced recombination rate of the photogenerated charge. EPR analysis and experiments with radical inhibitors demonstrated that OH● and O2–● radicals contribute to the photocatalytic process. In addition, the heterostructure exhibits excellent photostability under sunlight, losing only 5.1 % efficiency after four reuse cycles.