Exploration of the effect of the preparation conditions on the morphology and structure of g-C3N4 intending to evaluate the photocatalytic performance
摘要
Graphitic carbon nitride (g-C3N4) was synthesized by a hydrothermal-calcination method with melamine and urea were used as raw materials without using hard and soft templates as well as organic solvents, which include the concept of easy, green, and economical synthesis. In this article, by adjusting the synthesis conditions, supramolecules and g-C3N4 with different morphologies of irregular plates, nanoparticles, plates with holes, polyhedral, stacked sheets, and tubes were obtained. By manipulating the weight ratio of the precursors and changing the heating time, the bandgap energy was reduced to 2.61 eV and the specific surface area increased to 126.98 m2 g−1. The effect of important parameters like the pH, pollutant concentration, and photocatalyst dose in the degradation of Rhodamine B was investigated. The nanotube sample with a urea to melamine ratio of 1.5, heated for 16 h in an autoclave, demonstrated the best performance, achieving 98.3% degradation efficiency of RhB after 30 min of visible irradiation under optimum conditions. This enhanced photocatalytic performance is attributed to a narrowed bandgap, improved charge carrier separation and lifetime, and increased surface area. Using the LC–MS results, intermediate molecules and the path of RhB degradation were identified. The synthesized g-C3N4 showed good stability after 5 photocatalytic cycles.