Preparation of g-C3N4/BiOX (X = Cl, Br, I) composites, and their photocatalytic activity under visible light irradiation

g-C3N4/BiOX (X = Cl, Br, I) composite photocatalysts have been prepared by means of a facile immersion–hydrolysis method. The microstructural and morphological characteristics of the as-prepared composite photocatalysts were investigated by means of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. The photodegradation performance of both g-C3N4/BiOCl and g-C3N4/BiOBr composites was superior to that of pure g-C3N4 or the corresponding bismuth oxyhalides, possibly because of efficient separation of photogenerated carriers at the interface between g-C3N4 and BiOX (X = Cl, Br). The photostability of as-prepared g-C3N4/BiOX (X = Cl, Br) composites was also investigated.