The Synthesis and Photophysical Performance of a Novel Z-Scheme HoFeSbO/BiYbO Heterojunction Photocatalyst and the Photocatalytic Degradation of Ciprofloxacin Under Visible Light Irradiation.

A pyrochlore-type crystal structure photocatalytic nanomaterial, HoFeSbO, was successfully synthesized using a hydrothermal method. Additionally, a fluorite-structured BiYbO was prepared via rare earth Yb doping. Finally, a novel HoFeSbO/BiYbO heterojunction photocatalyst (HBHP) was fabricated using a solvothermal method. The crystal structure, surface morphology, and physicochemical properties of the samples were characterized using XRD, a micro-Raman spectrometer, FT-IR, XPS, ultraviolet photoelectron spectroscopy (UPS), TEM, and SEM. The results showed that HoFeSbO possessed a pyrochlore-type cubic crystal structure (space group Fd-3m, No. 227), while BiYbO featured a fluorite-type cubic structure (space group Fm-3m, No. 225). The results of the degradation experiment indicated that when HBHP, HoFeSbO, or BiYbO was employed as a photocatalytic nanomaterial, following 140 min of visible light irradiation, the removal efficiency of ciprofloxacin (CIP) reached 99.82%, 86.15%, or 73.86%, respectively. This finding strongly evidenced the remarkable superiority of HBHP in terms of photocatalytic performance. Compared to the individual catalyst HoFeSbO, BiYbO, or N-doped TiO, the removal efficiency of CIP by HBHP was 1.16 times, 1.36 times, or 2.52 times higher than that by HoFeSbO, BiYbO, or N-doped TiO, respectively. The radical trapping experiments indicated that in the CIP degradation process, the hydroxyl radical owned the strongest oxidation ability, followed by the superoxide anion and the photoinduced hole. These studies are of great significance for the degradation of antibiotics and environmental protection.