Cobalt promoted TiO₂/GO for the photocatalytic degradation of oxytetracycline and Congo Red

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.