Influence of heated stirring time on the photocatalytic activity of Mg-modified g-C3N4

Abstract

In this study, magnesium-doped graphite carbon nitride (Mg-doped g-C₃N₄) material was successfully synthesised via a simple chemical method, with reaction times ranging from 3 to 18 hours, followed by thermal treatment at 90°C. The crystal structure and chemical states of the material were characterised by X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), while the optical properties were evaluated through UV-Vis absorption and photoluminescence (PL) spectroscopy. The photocatalytic performance was investigated through the degradation of Rhodamine B (RhB) solution under irradiation from a Xenon lamp and natural sunlight. The results revealed that all Mg-doped samples exhibited superior photocatalytic activity compared with pristine g-C₃N₄. This enhancement is attributed to the presence of Mg²⁺ cations acting as electron “trapping centres”, which suppress the recombination of photogenerated electron-hole pairs. Moreover, the incorporation of Mg into the heptazine framework increases the specific surface area, thereby promoting the overall photocatalytic efficiency of the materials. The results of this study indicate that doping g-C₃N₄ with 10% Mg and selecting an appropriate synthesis time are effective strategies for enhancing its photocatalytic performance.