Novel BiOCl–C3N4 heterojunction photocatalysts: In situ preparation via an ionic-liquid-assisted solvent-thermal route and their visible-light photocatalytic activities

Abstract Novel BiOCl–C 3 N 4 heterojunctions were synthesized through an in situ ionic-liquid-assisted solvent-thermal method, through which a highly dispersed heterointerface was formed with almost no loss of C 3 N 4 . The composites were characterized using X-ray diffraction, high-resolution transmission microscopy, scanning electron microscopy, nitrogen adsorption–desorption measurements, UV–visible light diffusion reflectance spectrometry, Fourier-transform infrared spectroscopy, and photoluminescence spectroscopy. The results indicated that BiOCl was dispersed on C 3 N 4 to form heterojunction structures with high specific surface area and the ability to absorb visible light. The photocatalytic results for the degradation of methyl orange (MO) indicated that the most active heterojunction proportion is 1BiOCl:1C 3 N 4 , which increased the visible light photocatalytic activity 3.3-fold relative to that of a sample of the mechanically mixed counterpart of this composition. The enhanced performance was induced by the high separation efficiency of photoinduced electrons from the LUMO of C 3 N 4 injected into the CB of BiOCl. We also determined that the enrichment of holes in the HOMO of the C 3 N 4 in the present BiOCl–C 3 N 4 heterojunctions played a dominant role in the oxidation of MO.