Novel Two-Stage Method of Preparing Graphitic Carbon Nitride Doped by Chlorine for Photocatalytic Hydrogen Evolution and Photocurrent Generation

In this work, graphitic carbon nitride doped by chlorine was prepared by a two-stage procedure for the first time. At the first stage, melamine was hydrothermally treated with glucose; at the second stage, the resulting precursor was calcined in a mixture with ammonium chloride. The obtained samples were studied using a set of physicochemical methods, such as X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy, and photoelectrochemical methods. All of the synthesized photocatalysts were tested in the reaction of photocatalytic hydrogen production from basic solutions of triethanolamine. The highest rates of hydrogen evolution and short-circuit current densities were obtained with a photocatalyst prepared by the calcination of a mixture consisting of 30% ammonium chloride and 70% melamine. The catalytic activity of this sample was 1332 μmol h–1 g–1, and it was higher than the catalytic activity of carbon nitride prepared by the calcination of melamine without pretreatment by a factor of 22.