Graphitic carbon nitride photocatalysis: the hydroperoxyl radical role revealed by kinetic modelling

Abstract

Metal-free graphitic carbon nitride (GCN) is an optical semiconductor with the advantage of in situ H₂O₂ generation parallel to pollutant removal. The photocatalytic degradation mechanism using GCN is attributed to a series of reactions with reactive oxygen species and photogenerated holes. However, the role of each species in the photocatalytic process kinetics remains a challenge. This work provides novel photodegradation kinetic data through a modelling approach using the Kintecus software for the first time in heterogeneous photocatalytic reactions. The results were validated by double fitting of simultaneous phenol removal and H₂O₂ formation. The role of dissolved oxygen and intermediate products are also investigated. Sophisticated techniques, as photoacoustic spectroscopy for energy-resolved distribution of electron traps and diffuse reflectance spectroscopy for determination of band energies, aid to clarify the behaviour of GCN. This paper identifies the oxidation routes contributors and carefully describes the GCN photocatalytic simultaneous phenol degradation and H₂O₂ generation.