Green Synthesis of ZnO‐Ag ₃ PO ₄ Heterojunctions Using <i>Pentas schimperiana</i> Leaf Extract for Enhanced Photocatalytic and Antibacterial Applications

Abstract

ABSTRACT In this study, the green synthesis of ZnO, Ag 3 PO 4 , and ZnO‐Ag 3 PO 4 nanomaterials was presented for degrading methylene orange (MO) and bacterial diseases from wastewater. ZnO‐Ag 3 PO 4 nanocomposite was capped by polyvinyl alcohol (PVA) and Pentas schimperiana leaf extraction for surface modification. The synthesized nanomaterials were characterized by advanced techniques. The modified band gap from 3.25 eV to 2.48 eV was observed for ZnO particles when Ag 3 PO 4 loaded on its surface. The photocatalytic activity of the synthesized materials over MO was examined. A 96% of MO was degraded when ZnO‐Ag 3 PO 4 materials was used. Recyclability of the as‐synthesized composite was explored using four consecutive experiments and the degradation efficacy for the fourth cycle was observed to be 79%. Comparatively, at the fourth cycle, decreasing efficiency was signified. A possible photocatalytic degradation mechanism was proposed. The antibacterial and antioxidant potentials for the prepared materials were assessed. The ZnO‐Ag 3 PO 4 nanocomposite exhibited superior potentials: 24.42 ± 0.44 and 23.23 ± 0.43 mm against Staphylococcus aureus and Escherichia coli at 100 µg/mL, respectively. The antioxidant efficacy (91.43%) of ZnO‐Ag 3 PO 4 was observed to be higher relative to Ag 3 PO 4 (72.41%) and ZnO (63.48 %). The ZnO‐Ag 3 PO 4 nanomaterial revealed outstanding photocatalytic and biological potential.