A family of titania derived nanocomposites synthesized via sol-gel and hydrothermal routes exhibit excellent performance for the photocatalytic degradation of two important exemplar water pollutants, oxytetracycline and Congo Red. Low loadings of Co3O4 nanoparticles dispersed over the surfaces of anatase TiO2 confer visible light photoactivity for the aqueous phase decomposition of organics through the resulting heterojunction and reduced band gap. Subsequent modification of these Co3O4/TiO2 composites by trace amounts of graphene oxide nanosheets in the presence of a diamine linker further promotes both oxytetracycline and Congo Red photodegradation under simulated solar and visible irradiation, through a combination of enhanced photoresponse and consequent radical generation. Radical quenching and fluorescence experiments implicate holes and hydroxyl radicals as the respective primary and secondary active species responsible for oxidative photodegradation of pollutants

Graphitic carbon nitride (g-C₃N₄) is a promising material for photocatalytic applications such as solar fuels production through CO₂ reduction and water splitting, and environmental remediation through the degradation of organic pollutants. This promise reflects the advantageous photophysical properties of g-C₃N₄ nanostructures, notably high surface area, quantum efficiency, interfacial charge separation and transport, and ease of modification through either composite formation or the incorporation of desirable surface functionalities. Here, we review recent progress in the synthesis and photocatalytic applications of diverse g-C₃N₄ nanostructured materials, and highlight the physical basis underpinning their performance for each application. Potential new architectures, such as hierarchical or composite g-C₃N₄ nanostructures, that may offer further performance enhancements in solar energy harvesting and conversion are also outlined.