Green synthesized plasmonic Pd–ZnO nanomaterials for visible light-induced photobiogas production from industrial wastewater

Abstract

Plasmonic Pd–ZnO nano photocatalysts synthesized via a green chemistry approach represent an innovation of visible-light-induced photocatalysis that can be applied for photobiogas production from organic dye pollutants. Different plasmonic Pd–ZnO nanophotocatalysts have been synthesized via green microwave-assisted methods using orange peel extract as a capping agent by adding different proportions (3, 5, and 7 wt%) from Pd-metal plasmons. This fast and green innovative method anchored well distribution of Pd-metal plasmons (2-5 nm) on the surface of ZnO (17–27 nm). XRD has investigated the nanostructures' crystallographic, morphological, and optical characteristics, XPS, TEM, UV–Vis DRS, and as.BET surface area analysis. A higher surface area data have been achieved by incorporating Pd plasmons from 9.2 m2 g−1 in pure ZnO to 16.9 m2 g−1 in 7% Pd–ZnO. The analysis of XPS spectra shows an increase of the lattice oxygen (OL) from 62.36% to 65.08%, suggesting an increase in the number of oxygen vacancies on the surface of the Pd–ZnO plasmonic photocatalysts that leads to enhancing its photocatalytic performance. UV–Vis optical spectra of the different Pd–ZnO photocatalysts reveal the visible light absorption capability due to the localized surface plasmonic resonance effect (LSPR). The photocatalytic activity of the obtained Pd–ZnO nanomaterials has been tested on the photobiogas production during the photocatalytic destruction of Reactive Yellow 15 (R.Y.) in two prototype photobiogas reactors, cylindrical UV reactor and a pilot-scale CPC solar reactor, under nitrogen atmosphere. A higher yield of biogas (CH4) and hydrogen (H2) gases have been achieved by the effect of Pd plasmons on the ZnO photocatalyst.