Photocatalytic and photo-electrochemical behavior of novel SnO2-modified-g-C3N4 for complete elimination of tetracycline under visible-light irradiation: Slurry and fixed-bed approach

Abstract

We present a novel and low-cost SnO2-modified-g-C3N4 (SnCN)-coated on natural pebbles through a unique fabrication method. Initially, a succession of unique SnO2-modified-g-C3N4 (SnCN) photocatalysts was prepared via a facile hydrothermal method. The addition of SnO2 into g-C3N4 not only reduced the band-gap energy and recombination ability of the electron-hole pairs but also drastically augmented the pore volume and surface area. The BET surface area of the 4% modified sample (69.1022 m2/g) was approximately 4.5 times higher in comparison to the pure form (16.2567 m2/g). Notably, the photocatalytic performance of the SnCN samples under visible light irradiation was significantly improved, with tetracycline 40 ppm (TC) removal of up to 90.29% attained after 2 h at the optimized initial pH of 10 in the presence of 4% SnO2 modification. With a view toward the practical applications, the as-prepared catalyst was successfully immobilized over low-cost, highly durable and eco-friendly pebbles as confirmed through characterization techniques. In addition to the photocatalytic process, the extended applications of the as-prepared photocatalyst were also studied by analyzing the photoelectrochemical (PEC) behaviors through transient photocurrent response, Mott-Schottky plots, and electrochemical impedance spectroscopy (EIS) spectra.