Facile synthesis of ZnO/CeO2/CeFeO3 photocatalysts sensitive to visible light with tandem n-n heterojunctions and improved performance towards tetracycline and dye effluent removals

Abstract

Nowadays, ZnO-based photocatalysts are very effective in wastewater treatment. Herein, CeO2 and CeFeO3 nanoparticles were anchored on ZnO through a coprecipitation-calcination procedure. The fabricated materials were studied by TEM, EDX, SEM, XRD, HRTEM, XPS, PL, UV–vis DRS, BET, BJH, FTIR, and EIS analyses. The optimized ZnO/CeO2/CeFeO3 nanocomposite showed significant performance for the degradation of tetracycline hydrochloride, amoxicillin, Congo red, and Fuchsine with rate constants of 313 × 10−4, 104 × 10−4, 204 × 10−4, and 163 × 10−4 min−1, which was 24.1, 1.44, 20.4, and 2.03 times higher than ZnO, respectively. Moreover, the reduction of Cr(VI) to Cr(III) (189 × 10−4 min−1) over the ZnO/CeO2/CeFeO3 photocatalyst was almost 2.12 times faster than the ZnO photocatalyst (88.7 × 10−4 min−1). Besides, the photocatalyst presented remarkable stability after four cycles in the photodegradation of tetracycline hydrochloride contaminant. The purified solution over the photocatalyst was also tested in terms of biocompatibility. The optical, electrochemical, and textural analyses attributed the enhanced activity to the effective production and separation of charge carriers, facile transfer of electron/hole pairs, and promoted textural characteristics. The enhanced charge segregation was ascribed to the developing tandem n-n heterojunctions among ZnO, CeO2, and CeFeO3.