Solvent-free synthesis of an efficient heterojunction Cr₂O₃/g-C₃N₄ composites for the photocatalytic removal of TC-HCl antibiotic and RO16 dye

Cr₂O₃/g-C₃N₄ photocatalyst was successfully synthesized via the one-pot thermal polycondensation method by mixing different ratios of CrCl₃.H₂O and thiourea. Thiourea was used as the precursor for building g-C₃N₄. All samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM–EDS), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS), and electrochemical experiment (photocurrent and EIS). The photocatalytic performance of the composites was studied by the photodegradation process of tetracycline hydrochloride (TC-HCl) and reactive orange 16 (RO16) under visible light irradiation. The results showed that the 1%Cr₂O₃/g-C₃N₄ was the most effective photocatalyst with 94.9% (30 min) and 80.6% (90 min) for degradation of RO16 and TC-HCl, respectively, when compared with the other ratios. Additionally, from the reactive species trapping test, superoxide radical was the major reactive species in this reaction. Finally, this material could be reused with great efficiency with 5 and 7 times for TC-HCl and RO16, respectively. The synthesized composites manifest the great potential for the wastewater treatment industry.