Synergistic enhancement of photocatalytic and antimicrobial efficacy of nitrogen and erbium co-doped ZnO nanoparticles

Abstract

Using the chemical co-precipitation approach, a series of nitrogen (N) and erbium (Er) co-doped ZnO nanoparticles (NPs) was effectively synthesized to enhance the photocatalytic and antibacterial activities. Several characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-vis, and photoluminescence (PL) spectroscopy, were carried out to validate the evaluated photocatalytic and antibacterial activities. XRD analysis confirms the pure wurtzite ZnO phase without the presence of any secondary phase. XPS analysis confirms the successful incorporation of nitrogen and erbium into the ZnO matrix. The optical bandgap of ZnO calculated from UV-vis spectroscopy shows a redshift after Er–N co-doping, with the lowest bandgap of 3.215 eV calculated for Zn0.97Er0.03N0.01O0.99 NPs. SEM images demonstrate the formation of nanorods after N–Er co-doping, followed by gradually increased rod diameter and length after N–Er co-doping. Moreover, the photocatalytic activities of ZnO samples were measured by their ability to facilitate the photodegradation of Rhodamine B under UV irradiation. ZnO with 1 mol% N doping exhibits 88% photodegradation of RhB under UV light within 360 min, and the photodegradation and antibacterial activity are greatly improved with Er co-doping. In fact, 3 mol% Er-1 mol% N doped ZnO NPs demonstrate the highest photocatalytic activity, with approximately 96% degradation after 360 min, as well as superior antibacterial activity against Staphylococcus aureus (Gram-positive bacteria) and Pseudomonas aeruginosa (Gram-negative bacteria) with the highest zone of inhibition (ZOI) of 16 nm, due to nanorod formation, increased reactive oxygen species (ROS), and decreased electron–hole recombination, as validated by SEM, XPS, and PL spectroscopy.