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In this study, pure ZnO and iron (Fe) and cobalt (Co) co-doped ZnO nanoparticles were synthesized by varying Fe and Co concentrations using the co-precipitation method. The physical properties of as-prepared samples were investigated through XRD, FTIR, SEM, and UV–vis spectroscopy. X-ray diffraction confirmed the strong influence of Fe and Co ions on structural parameters without disturbing the basic ZnO hexagonal structure. The microstructural study was executed by using the Scherrer, W–H, and SSP methods. FTIR confirmed the presence of Zn–O, and Zn–M–O (M = Fe, Co) vibrational modes, which further confirmed the successful incorporation of dopants ions. The energy bandgap (E g) extracted from UV–vis spectra has shown red-shift (3.37–2.7 eV) for decreasing Fe contents, whereas blue-shift (3.37–3.39 eV) for increasing Co concentration. SEM was used to investigate surface morphology, which represents the high rate of agglomeration. The photocatalytic test was performed on grown samples against various dyes and also observed the effects of varying concentrations of Fe and Co ions. The maximum degradation efficiency (98.8%) at 6%Fe and 4%Co under direct sunlight in 60 min against methylene blue (MB) was achieved. The photocatalytic activity of optimized concentration (6%Fe and 4%Co) was further tested against cresol red (CR), methyl orange (MO), safranin-O (SO), rhodamine-B (RhB), and methyl red (MR) dyes. The maximum degradation efficiency against MR dye (96.0%) was observed. The antibacterial test against Staphylococcus aureus and Klebsiella pneumoniae bacterial strains have shown that co-doped ZnO nanoparticles have a higher activity as compared to pristine ZnO, and furthermore, the sample with 6%Fe and 4%Co concentration exposed the highest antibacterial actively for both bacterial strains. [ABSTRACT FROM AUTHOR]

Novel direct dual Z-scheme ZnO-Er 2 O 3 -Nd 2 O 3 @rGO heterostructured nanocomposite along with simple ZnO-Er 2 O 3 -Nd 2 O 3 nanocomposite was prepared by co-precipitation route. The X-ray diffraction pattern exhibited the diffraction peaks associated with ZnO (hexagonal), Er 2 O 3 (cubic), and Nd 2 O 3 (hexagonal) in both nanocomposites. The FTIR spectra further confirmed the formation of nanocomposites. The energy bandgap of simple and rGO decorated nanocomposites were 3.1 and 2.82 eV. The antibacterial characteristics of grown samples showed that the rGO anchored nanocomposite has higher antibacterial activity as compared to simple nanocomposite. The ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite exhibited higher photodegradation (97.0%) against methylene blue (MB) than simple nanocomposite (86.0%). The effectiveness of grown ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite as photocatalyst was also tested for degradation of other dyes such as RhB, MO, CR, and SO. The effect of operating parameters was investigated for ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite. A possible conventional heterojunction and Z-scheme for the degradation using ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite has been designed to elucidate the photocatalytic mechanism. • ZnO-Er 2 O 3 -Nd 2 O 3 and ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposites successfully prepared. • The photocatalytic application was studied using MB, RhB, MO, CR and SO dyes. • The effect of operating parameters for the degradation of SO dye investigated. • The antibacterial activity against different bacterial strains was investigated. [ABSTRACT FROM AUTHOR]