Hydrothermal–ultrasonication-assisted fabrication of Ce-doped ZnO/g-C3N4 heterojunctions for enhanced visible-light degradation of dye and drug pollutants

The rapid recombination of photogenerated charge carriers (e − /h + ) reduces the quantum efficiency of photocatalytic materials, restricting their practical applicability. In this study, an active Ce-ZnO/g-C 3 N 4 heterojunction with staggered band alignment was fabricated via ultrasonication and hydrothermal routes to delay the recombination rate of e − /h + pairs. Initially, zinc oxide (ZnO) and its cerium-modified counterpart (Ce-ZnO) were fabricated following the hydrothermal method, and the modified material was assembled with graphitic carbon nitride (g-C 3 N 4 ) via sonication to construct the Ce-ZnO/g-C 3 N 4 heterojunction. The synthesized pure, modified, and heterojunction materials were characterized to reveal their structural features, morphology, optical properties, and charge separation/transfer characteristics. The photocatalytic activity was determined by degrading Rhodamine B textile dye (RhB) and levofloxacin antibiotic (LVF), which are representative organic pollutants. Compared with its pure counterparts, the constructed heterojunction-based material shows enhanced catalytic activity under visible light, which can be attributed to active heterojunction formation, which delays the rapid recombination of e − /h + by facilitating charge separation/transfer. The Ce-ZnO/g-C 3 N 4 material displayed 96 % RhB degradation and 87 % LVF degradation under visible light exposure following 1st-order kinetics. The generation of reactive oxygen species (HO • and O 2 •− ) during the degradation of RhB and LVF was tracked using a scavenging experiment. The designed heterojunction-based material with promising photocatalytic activity, stability, and reusability holds potential for the degradation of organic pollutants.