Enhanced visible-light utilization with ZnCo2O4–BiErWO6 heterojunctions towards photocatalytic degradation of antibiotics

Abstract

Herein, zinc cobaltite–bismuth erbium tungstate (ZC–BE) nanocomposites have been successfully synthesized by a simple hydrothermal method. The hybrid ZC–BE nanocomposites was carefully investigated using field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), diffuse reflectance spectroscopic measurements (DRS), Raman, and electrochemical impedance studies (EIS) respectively. The photocatalytic degradation of model pollutant ciprofloxin (CIP) was evaluated using the as-prepared ZC–BE samples upon visible-light irradiation. The photocatalytic degradation efficiency of the nanocomposite with 15 wt% ZC composition displayed an excellent degradation rate of CIP of 91.24% within 120 min which was higher than that of pure ZnCo2O4 (ZC) and BiErWO6 (BE) alone. Such an improvement was primarily credited to the construction of a suitable heterojunction between BE and ZC, superior visible-light absorption and sluggish recombination of photogenerated electron–holes in the photocatalyst process. Based on the experimental results, a plausible degradation mechanism for the CIP under the visible light was discussed. Hence, ZC–BE heterostructure may be a promising visible-light-responsive photocatalyst for removing pharmaceutical pollutants in wastewater.