NiO nanoparticles synthesized by using Tagetes erecta L leaf extract and their activities for photocatalysis, electrochemical sensing, and antibacterial features

[Display omitted] •Nickel oxide nanoparticles (NiONPs) were prepared using Tagetes erecta L leaf extract.•Microwave irradiation method for the synthesis gave smaller particle size compared to reflux method.•The synthesized NiONPs exhibited photocatalytic activity with 59% degradation of MB on 10 mg/L dosage.•The synthesized NiONPs represented the high sensitive for glucose sensore with 83 µM limit of detection.•The synthesized NiONPs exhibited excellent antibacterial activity. In this study, the green synthesis of NiO nanoparticles (NiO NPs) by using the leaf extract of Tagetes erecta L as the bio-reductor was reported. NiO NPs were synthesized by two methods, viz. microwave irradiation and the reflux method, respectively, and physicochemical properties of the as-formed NiO NPs were characterized by XRD, SEM-EDX, TEM, and XPS analyses. The chemical properties of NiO NPs were evaluated as a photocatalyst for the degradation of methylene blue and as a glucose sensor for electrochemical sensing. Moreover, their biological property was examined as an antibacterial agent. Results revealed that the microwave-assisted green synthesis successfully affords NiO NPs with a particle size of 18.2 nm. In addition, NiO NPs were demonstrated to be an efficient photocatalyst and an effective electrochemical sensor with a degradation efficiency (53% for 120 min) comparable to those reported in similar studies, and the feasibility for glucose analysis was demonstrated by a limit of detection of less than 83 µM and a sensitivity of 2556.41 µA. mM−1.cm−2.. From the antibacterial activity test, nanoparticles were found to be effective against Gram-positive and Gram-negative bacteria, with better antibacterial activity toward Gram-positive bacterial strains.