Designing and investigation of enhanced photocatalytic and antibacterial properties of 3d (Fe, Co, Ni, Mn and Cr) metal-doped zinc oxide nanoparticles

In the present study, transition metal (Fe, Cr, Ni, Co and Mn)-doped ZnO nanoparticles (TM-ZN NPs) were synthesized via the chemical co-precipitation method. The effect of TM doping on the photocatalytic and antibacterial activity of ZnO (ZN) nanoparticles has been studied. Important analytical techniques characterized the synthesized materials. The XRD analysis verified the TM doping in ZN and confirmed the wurtzite hexagonal structure of ZN and TM-ZN NPs. SEM and TEM studied the synthesized samples' morphology and size, and the compositional analysis was performed by EDX spectroscopy. TM-ZN NPs showed enhanced photocatalytic and antibacterial activity than ZN NPs. In particular, Mn-doped ZnO nanoparticles (MnZN NPs) exhibited the highest bactericidal efficiency against Gram-negative and Gram-positive strains and maximum MB photocatalytic degradation (98% in 120 min) under sunlight irradiations. The notable increase in the photocatalytic and antibacterial activity of the synthesized TM-ZN NPs might be attributed to a decrease in their bandgap and suppression of e-h pairs recombination due to the induction of additional energy levels below the CB of ZN. The MnZN NPs showed good photocatalytic stability even after six consecutive cycles. Furthermore, a conceivable bactericidal and MB degradation mechanism over the MnZN NPs has been suggested. •Fabrication of transition metals (Cr, Fe, Mn, Co & Ni) doped-ZnO nanoparticles.•Band gap tuning of ZnO by doping with transition metals (Cr, Fe, Mn, Co & Ni).•Mn doped-ZnO nanoparticles exhibits better photocatalytic and antibacterial efficiency than (Cr, Fe, Co & Ni) doped-ZnO nanoparticles.•Photocatalytic MB degradation rate of Mn doped-ZnO is 3.5 times higher than ZnO.•Mn doped-ZnO nanoparticles exhibits excellent recyclability and sustainability.