Microwave-assisted synthesis of chalcopyrite/silver phosphate composites with enhanced degradation of rhodamine b under photo-fenton process

A new composite by coupling chalcopyrite (CuFeS₂) with silver phosphate (Ag₃ PO₄) (CuFeS₂ /Ag₃ PO₄) was proposed by using a cyclic microwave heating method. The prepared composites were characterized by scanning and transmission electron microscopy and X-ray diffraction, Fourier-transform infrared, UV–Vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Under optimum conditions and 2.5 W irradiation (wavelength length > 420 nm, power density = 0.38 Wcm⁻²), 96% of rhodamine B (RhB) was degraded by CuFeS₂ /Ag₃ PO₄ within a 1 min photo-Fenton reaction, better than the performance of Ag₃ PO₄ (25% degradation within 10 min), CuFeS₂ (87.7% degradation within 1 min), and mechanically mixed CuFeS₂ /Ag₃ PO₄ catalyst. RhB degradation mainly depended on the amount of hydroxyl radicals generated from the Fenton reaction. The degradation mechanism of CuFeS₂ /Ag₃ PO₄ from the photo-Fenton reaction was deduced using a free radical trapping experiment, the chemical reaction of coumarin, and photocurrent and luminescence response. The incorporation of CuFeS₂ in Ag₃ PO₄ enhanced the charge separation of Ag₃ PO₄ and reduced Ag₃ PO₄ photocorrosion as the photogenerated electrons on Ag₃ PO₄ were transferred to regenerate Cu²⁺ /Fe³⁺ ions produced from the Fenton reaction to Cu⁺ /Fe²⁺ ions, thus simultaneously maintaining the CuFeS₂ intact. This demonstrates the synergistic effect on material stability. However, hydroxyl radicals were produced by both the photogenerated holes of Ag₃ PO₄ and the Fenton reaction of CuFeS₂ as another synergistic effect in catalysis. Notably, the degradation performance and the reusability of CuFeS₂ /Ag₃ PO₄ were promoted. The practical applications of this new material were demonstrated from the effective performance of CuFeS₂ /Ag₃ PO₄ composites in degrading various dyestuffs (90–98.9% degradation within 10 min) and dyes in environmental water samples (tap water, river water, pond water, seawater, treated wastewater) through enhanced the Fenton reaction under sunlight irradiation.