Employing enzymes as co-catalysts with semiconducting oxides is one of the cost-effective and nature-friendly ways for photocatalytic decomposition of toxic organic dye molecules. In the present study, enzymepowered zinc oxide nanomaterial was prepared using vermiwash derived from the earthworm (Endrilus eugeniae) culturing unit. Two sets of samples were prepared via a simple soft-chemical method by applying heat (i) during the stirring stage of synthesis and (ii) as post-synthesis heat treatment. The effect of this heat treatment on the photocatalytic efficiency of the synthesized nanoproduct has been studied. The study on the activity of enzymes present in the nanoproduct, structural studies through X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photocatalytic degradation studies are fitly correlated among them to address the observed enhancement in the photocatalytic activity. The results provide strong evidence to support the potential use of vermiwash for synthesising nano-sized photocatalysts that can be used to treat toxic organic pollutants, such as methylene blue.

A series of Ba$_{1.97–x}$Eu$_{0.03}$Dy$_x$V$_2$O$_7$ (x = 0.01, 0.02, 0.03, 0.04 and 0.05) phosphor materials were synthesized by hydrothermal method. Phase purity, structural, optical and luminescence characteristics of as-synthesized phosphorshave been studied using powder X-ray diffraction (PXRD), UV–visible spectroscopy and fluorescence spectrometry. The XRD patterns of as-synthesized phosphors were indexed and predicted as triclinic structure. The broad absorption in the UV region was originated from [VO$_4$]$^{3-}$ group charge transfer and the sharp peaks observed in the visible to near-infrared (NIR) region was originated from Eu$^{3+}$/Dy$^{3+}$ ions charge transfer. In photoluminescence (PL) spectra, the broad emission peak observed from 400 to 570 nm was due to the charge transfer band of [VO$_4$]$^{3-}$ group. A sharp peak observed from 570 to 710 nm were due to the charge transition of Eu$^{3+}$/Dy$^{3+}$ ions. The PL spectra recorded for different excitations at 268, 344, 335, 346, 346 and 339 nm, emitted bluish white colour with slight changes in its Commission International de l'Eclairage coordinate values. The white colour emission of Ba$_{1.97–x}$Eu$_{0.03}$Dy$_x$V$_2$O$_7$ phosphors was observed by the irradiation under the UV light 365 nm. Hence, the results have suggested that the as-prepared phosphor materials are the potential candidates in the fabrication of a UV or near-UV chip-excited white light-emitting diode.