Enhanced photocatalytic degradation of methylene blue and methyl orange using biogenic ZnO NPs synthesized via Vachellia nilotica (Babool) leaves extract

Biogenic zinc oxide (b-ZnO) NPs were synthesized via the leaf extract of Vachellia nilotica (Babool) due to their rich source of bioactive complexes, which have great potential as a reliable, sustainable, and eco-friendly system. Sharp peaks in the XRD pattern of b-ZnO NPs confirmed the hexagonal wurtzite crystal structure. The crystallite size, D, of b-ZnO, decreased from 22.22 nm to 10.13 nm, and the lattice strain (τ) increased from 5.22 × 10−3 to 11.47 × 10−3 as the material changed from synthetic to biogenic, respectively. The Eg of b-ZnO was observed to be 3.37 eV. The specific surface area, total pore volume and average pore diameter of ZnO and b-ZnO NPs were increased from 9.5 to 34 m2/g, 0.3536–0.3854 cm3/g, and 17.24–19.56 nm, respectively. The photocatalytic degradation of b-ZnO increased from 72% to 80% for MO dye, from 87% to 93% for MB dye and completely degraded MB within 2 h. This work presents an essential advancement towards achieving enhanced photocatalytic performance to reduce water pollutants using b-ZnO and will guide the use of biogenic nanomaterials for photocatalytic applications. [Display omitted] •Biogenic ZnO NPs synthesized by hydrothermal precipitation using Vachellia nilotica extract.•The crystallite size, D, of b-ZnO, decreased from 22.22 nm to 10.13 nm.•The τ and δ of b-ZnO increased from 5.22 × 10−3 to 11.47 × 10−3, and from 2.025 × 1011 to 9.745 × 1011 cm−2.•Eg of b-ZnO NPs increased from 3.31 eV to 3.37 eV.•The photodegradation efficiency of MB and MO by b-ZnO NPs increased from 87 to 93% per 120 min and 72–80% per 90 min.