Fabrication of AgCl-decorated SrMoO_4-x heterojunctions for remarkably enhanced photodegradation of emerging contaminants: performance and mechanism insights

The need for effectively wastewater treatment is becoming urgent than before because of the serious enrichment of organic pollutants in natural waters. Researchers are increasingly focusing on strontium (Sr)-based semiconductors and their composites for efficient environmental photocatalysis because of their remarkable advantages. In this work, an integrated solvothermal–chemical precipitation strategy was to synthesize defective SrMoO_4-x nanoparticles with rich oxygen vacancies and hybrid AgCl-decorated SrMoO_4-x heterojunctions for the photodegradation of emerging pollutants. The obtained AgCl/SrMoO_4-x composites showed improved solar-light harvesting capacity through AgCl modification when compared to the SrMoO_4-x nanoparticles. Moreover, the synthesized AgCl/SrMoO_4-x heterojunction composites showed the markedly improved charge separation efficiency and demonstrated outstanding photocatalytic efficiency in degrading carbamazepine and tetracycline pollutants. The apparent rate constant of the optimal AgCl/SrMoO_4-x-51 composite for carbamazepine degradation was measured at 0.04437 min⁻¹, which was approximately 15.20 times that of AgCl and an impressive 748.68 times that of the SrMoO_4-x nanoparticles. Furthermore, ESR analysis for the identification of reactive species revealed that photo-generated holes and ·O₂⁻ species played dominant roles in the degradation of carbamazepine under visible-light irradiation. The current work highlights the significant advantages of plasmonic SrMoO₄-based composite photocatalysts in effectively degrading emerging pollutants outperforming conventional heterojunction photocatalysts.