Enhanced Photocatalytic Activity of Semiconductor Nanocomposites Doped with Ag Nanoclusters Under UV and Visible Light

Abstract

Emerging contaminants (ECs) represent a wide range of compounds, whose complete elimination from wastewaters by conventional methods is not always guaranteed, posing human and environmental risks. Advanced oxidation processes (AOPs), based on the generation of highly oxidizing species, lead to the degradation of these ECs. In this context, TiO2 and ZnO are the most widely used inorganic photocatalysts, mainly due to their low cost and wide availability. The addition of small amounts of nanoclusters may imply enhanced light absorption and an attenuation effect on the recombination rate of electron/hole pairs, resulting in improved photocatalytic activity. In this work, we propose the use of silver nanoclusters deposited on ZnO nanoparticles (ZnO–Ag), with a view to evaluating their catalytic activity under both ultraviolet A (UVA) and visible light, in order to reduce energetic requirements in prospective applications on a larger scale. The catalysts were produced and then characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and inductively coupled plasma-optical emission spectrometry (ICP-OES). As proof of concept of the capacity of photocatalysts doped with nanoclusters, experiments were carried out to remove the azo dye Orange II (OII). The results demonstrated the high photocatalytic efficiency achieved thanks to the incorporation of nanoclusters, especially evident in the experiments performed under white light.

Semiconductor Electrode Materials Applied in Photoelectrocatalytic Wastewater Treatment—an Overview

“…This modification of semiconductor surface is also called "decoration". ZnO that is decorated with Ag nanoparticles is an example of the semiconductor material with enhanced photocatalytic activity [204][205][206].…”

Enhanced Solar Photocatalytic Activity of Thermally Stable I:ZnO/Glass Beads for Reduction of Cr(VI) in Tannery Effluent

“…Among different materials, glass substrate is a quite promising material to be used as a support because of its distinctive properties, i.e., higher surface area, superior adsorption, reduction in charge recombination, and transparency of glass are retained intact even after coating of the photocatalyst that will not disturb light penetration (photon flux) and rate of photocatalysis ( Amir et al, 2016 ; González-Rodríguez et al, 2020 ). Moreover, the shape and texture of the substrate also affect the available surface area for interaction with the pollutant ( Dong et al, 2021a ; Dong et al, 2021b ).…”

Obtaining Porous Zinc Oxide Ceramics Using Replica Technique: Application in Photocatalysis

“…Unlike developed countries that buy their fabrics pre-dyed, emerging countries such as China, India, and Brazil dye their fabrics locally, thus generating high levels of water dye contamination 1 . The problem of dyes is aggravated by the fact that such compounds are not eliminated by conventional waste treatments 3,4 . Therefore, alternative techniques such as advanced oxidation processes (AOPs) are required.…”

“…These are responsible for the mineralization of the organic components 6-8. Semiconductors are generally studied in the form of ultrafine powders due to their larger surface area. This characteristic enables greater exposure to oxidizing sites and favors photocatalysis 3,8,[16][17][18] . Nevertheless, for daily use in dye photocatalysis, it is necessary to use porous solid ceramics, which have larger surface areas than dense solids, since the material in particulate form (powders) is difficult to be recovered, compromising its regular use 18 .…”