Graphitic C3N4 and Ti3C2 nanocomposites for the enhanced photocatalytic degradation of organic compounds and the evolution of hydrogen under visible irradiation

Abstract

Graphitic carbon nitride (g-C3N4) and Ti3C2 nanocomposites were formed in aqueous dispersions under ultrasound, by the calcination of the mixtures of solid dicyandiamide (DCDA) and Ti3C2, and of dissolved DCDA and Ti3C2 in an aqueous phase. A heterojunction between g-C3N4 and Ti3C2, based on mutual chemical bonds, was created in all the synthetized materials as observed by X-ray photoelectron spectroscopy and also indicated by the decrease of band bap energies from 2.71 eV to 2.59 eV. The transfer of photoexcited electrons from g–C3N4 to Ti3C2 was documented by photoluminescence spectroscopy.Molecular modelling confirmed an observation provided by scanning electron microscopy that Ti3C2 was not equally dispersed in g-C3N4 but formed separated agglomerates.It was calculated that the interactions of g-C3N4/g-C3N4 and Ti3C2/Ti3C2 layers were stronger than those of g-C3N4/Ti3C2, and the interactions of Ti3C2 functionalized with oxygen were stronger than those of Ti3C2 functionalized with fluorine.The g-C3N4/Ti3C2 nanocomposites were further tested for photocatalytic oxidation reactions, such as the degradation of phenol and ofloxacin, and for reduction reactions, such as the evolution of hydrogen. Ofloxacin was degraded more efficiently (max. 79.4 %) than phenol (max. 20.1 %) during 120 min. The highest hydrogen yield was 76.9 μmol after 4 h of irradiation. All the photocatalytic experiments were performed under visible irradiation and confirmed the electron transfer from g-C3N4 to Ti3C2 enhancing the photocatalytic activity of g-C3N4.