Eco-friendly synthesis of zinc oxide nanoparticles as nanosensor, nanocatalyst and antioxidant agent using leaf extract of P. austroarabica

•The zinc oxide nanoparticles were effectively green synthesized using the aqueous leaf extract of P. austroarabica.•Green synthesized zinc oxide nanoparticles have highly fluorescent potential as practical probes for the detection of hazardous metal ions in environmental fields.•The zinc oxide nanoparticles are used as a highly efficient nanocatalyst for decomposing organic dyes.•Green synthesized zinc oxide nanoparticles have excellent antioxidant activity. To reduce the hazardous effects of toxic compounds employed in the synthesis of nanoparticles, researchers are looking at biological agents of reduction. The current work describes a green method for the biosynthesis of zinc oxide nanoparticles (ZnONPs) using leaf extract of P. austroarabica plant as biological reduction agent. The conditions of green synthesis were optimized to produce ideal size range of ZnONPs. ZnONPs were observed to have spherical and FCC crystals with particle size of 13.9 ± 4.3 nm, as confirmed by PXRD, SEM, and TEM results. The fluorescence technique demonstrated that ZnONPs are efficient probes for Cr(VI) ion, where LOD was 1.30 nM, that is one of the lowest LOD reported for sensing substances. The findings also explored that ZnONPs are very effective nano-catalyst for degrading of organic dyes, with decolorization of congo red and methylene blue dyes attaining 93.42 and 95.74 % in 10 and 15 min, respectively. Furthermore, the results indicated that ZnONPs have high antioxidant activity, due to the existing bioactive compounds on their surfaces. This study concludes that green synthesized ZnONPs can be used as environmental sensor for detection of hazardous substances, nanocatalyst for toxic dyes degradation and as antioxidants. This synthesis is highly effective, eco-friendly, low-cost, and non-toxic.