Enhancing visible-light photocatalytic activity of g-C3N4 by doping phosphorus and coupling with CeO2 for the degradation of methyl orange under visible light irradiation†
Abstract
CeO2/P-C3N4 composite photocatalysts were designed by doping phosphorus and coupling with CeO2 species. The structure and optical properties of the as-prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The photocatalytic activity of the CeO2/P-C3N4 was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation (λ > 420 nm). The results indicated that the optimum photocatalytic activity of CeO2/P-C3N4 at a weight content of 13.8% CeO2 for the degradation of MO was 7.4 and 4.9 times as high as that of pure CeO2 and g-C3N4, respectively. The remarkable enhancement of photocatalytic activity could be attributed to the synergistic effect between CeO2 and P-C3N4, which was found to extend the visible light absorption range, enhance visible light absorption and improve photogenerated electron–hole pairs separation efficiency after doping phosphorus and coupling with CeO2. Additionally, the superoxide radical anions (˙O2−) and holes (h+) were considered as the main reactive species during the photodegradation MO process, and a possible photocatalytic mechanism over CeO2/P-C3N4 composite photocatalyst was proposed based on the experimental results.