High efficiency of graphene/CoFe₂O₄ nanomaterial in the photocatalytic conversion of CO₂ dissolved in water under solar irradiation simulator

The present work describes the excellent performance of GH–CoFe₂O₄ photocatalysts based on graphene ferrite, synthesized using water rich in natural organic matter (NOM) as a solvent, for the photocatalytic reduction of CO₂ under artificial visible light, at ambient temperature and pressure. The nano-photocatalysts presented excellent photocatalytic activity, with high selectivity towards the conversion of CO₂ to methanol as the main product, for both semiconductors tested (CoFe₂O₄ and GH–CoFe₂O₄). The presence of graphene improved photoexcitation under visible light, decreasing the CoFe₂O₄ band gap value from 1.47 to 1.25 eV, resulting in decreased recombination of the e⁻/h⁺ pairs. The rates of formation of methanol were 1105.7 and 1389.9 µmol g⁻¹ h⁻¹ for CoFe₂O₄ and GH–CoFe₂O₄, respectively. The findings reveal the potential of photocatalysts based on ferrite and graphene for use in the conversion of CO₂ dissolved in water without any added chemical into high added-value products.