Advances and Challenges in Developing Efficient Graphene Oxide-Based ZnO Photocatalysts for Dye Photo-Oxidation

Abstract

The efficient remediation of organic dyes from wastewater is increasingly valuable in water treatment technology, largely owing to the tons of hazardous chemicals currently and constantly released into rivers and seas from various industries, including the paper, pharmaceutical, textile, and dye production industries. Using solar energy as an inexhaustible source, photocatalysis ranks among the most promising wastewater treatment techniques for eliminating persistent organic pollutants and new emerging contaminants. In that context, developing efficient photocatalysts using sunlight irradiation and effectively integrating them into reactors, however, pose major challenges in the technologically relevant application of photocatalysts. As a potential solution, graphene oxide (GO)-based zinc oxide (ZnO) nanocomposites may be used together with different components (i.e., ZnO and GO-based materials) to overcome the drawbacks of ZnO photocatalysts. Indeed, mounting evidence suggests that using GO-based ZnO nanocomposites can promote light absorption, charge separation, charge transportation, and photo-oxidation of dyes. Despite such advances, viable, low-cost GO-based ZnO nanocomposite photocatalysts with sufficient efficiency, stability, and photostability remain to be developed, especially ones that can be integrated into photocatalytic reactors. This article offers a concise overview of state-of-the-art GO-based ZnO nanocomposites and the principal challenges in developing them.

Cellulose Derived Graphene/Polyaniline Nanocomposite Anode for Energy Generation and Bioremediation of Toxic Metals via Benthic Microbial Fuel Cells

“…However, Figure 4 d shows bit tubular morphology in the composite material, which indicates the presence of PANI. Some flaky structures are also found, which also indicates the successful polymerization of aniline and composite formation with the GO sheet [ 43 ]. This nanocomposite formation was successful as the electrode is expected to enhance the electron transportation and collection of electrons.…”

New Insight on Photoisomerization Kinetics of Photo-Switchable Thin Films Based on Azobenzene/Graphene Hybrid Additives in Polyethylene Oxide

“…Azo dyes usually degrade under the influence of UV-irradiation, especially when a photocatalytic source of metal oxide is presented. ZnO, TiO2, SnO2, and CuO are mostly used as photocatalytic oxidation sources for the degradation process [ 18 , 19 ]. Methyl red is of those azo dyes which contain one or more azo groups (–N=N–) as a chromophore group that is influenced by UV absorption.…”

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

“…In such a way, in the period 2016-2020, nine excellent reviews must directly or indirectly do with ZnO-graphene composites, as described in Table 1. Therefore, only two reviews were explicitly found focused on the study of ZnO-graphene composites for benzoic [31] and dye photo-oxidation [32]. Concerning the reviews' number in the topics of ZnO-based materials and graphenebased materials applied in photocatalysis (i.e., 2010-2020), there are 265 and 230 publications, respectively (Figure 8).…”