Recent Developments in Functional Nanocomposite Photocatalysts for Wastewater Treatment: A Review

The dyes and nitroaromatic pollutants from wastewater have attracted much attention due to their huge safety risks to human society. At present, nanomaterials as catalysts of photocatalytic degradation have emerged as attractive and effective materials for wastewater treatment. On the one hand, much work has been focused on the search for nanomaterials with high catalytic activity, such as precious metal nanoparticles (NPs) and other advanced functional materials (e.g. graphene oxide (GO), MXenes, metal organic frameworks (MOFs), etc.). On the other hand, modifications of existing photocatalysts to enhance their photocatalytic activity have also been explored. In this paper, photocatalysts in various dimensions (including precious metal nanoparticles, nanofibres, 2D nanosheets such as MXenes, and MOFs) are been described. The deposition of nano photocatalysts by different techniques such as the formation of hydrogel structures to immobilize the catalysts, the treatment of nanocatalysts using electrospinning technique, and the formation of core-shell structures to enhance catalytic activity are also discussed. These techniques not only solve the aggregation of NPs due to their high surface energy but also impart unique properties to the nano photocatalysts. This review explores the synthesis of nano photocatalysts in different dimensions and their application in the catalytic degradation of dyes and nitro compounds, providing good leads for nano photocatalysts in materials design and environmental remediation.