Recent Progress in Heterostructured Photocatalysts for Contaminant Removal and Solar Fuels Production

Advanced oxidation processes using photocatalytic materials are a very promising approach to overcome the shortcomings of anthropogenic pollution. Over the past decades, numerous studies have focused on titanium dioxide, zinc oxide, hematite, bismuth vanadate, and molybdenum disulfide, establishing TiO2 as one of the most effective photocatalysts, with low cost, low toxicity, and high chemical stability. The investigation of their combinations as binary composite materials showed that they can also be utilized in environmental applications. Still, the performance of all catalysts can be significantly improved if coupled with other nanomaterials, such as carbon nitride, carbon dots, covalent organic frameworks, transition metal phosphides, or MXenes. In this context, this review presents the majority of their binary combinations in heterostructured composites as an attractive strategy for enhancing the separation mechanism of photogenerated charge carriers and the production of reactive radicals. The various charge transfer mechanisms at the heterojunction of such materials are presented, while specific applications underline the improvement in their properties and their effectiveness in wastewater treatment, the neutralization of pathogens, hydrogen evolution, and the CO2 photoconversion to hydrocarbons.