g-C3N4催化石墨化碳质材料的制备及光催化性能研究

通常采用以氢氧化物作为造孔剂,过渡金属硝酸盐或氯化物作为石墨化催化剂的传统两步法策略制备多孔石墨化碳材料。然而制备过程中多涉及有毒和腐蚀性试剂,且多步骤的过程耗时较长。本文以双氰胺为原料通过热缩聚反应得到g-C₃N₄,采用高铁酸钾为催化剂一步法实现g-C₃N₄的同步碳化-石墨化,并研究其光催化性能。与传统的两步法相比,该方法耗时少、效率高、无污染。与初始的g-C₃N₄材料相比,石墨化g-C₃N₄衍生碳质材料不仅显著改善了可见光的吸收,而且大大增强了光催化活性。研究了不同石墨化温度对g-C₃N₄衍生碳质材料在可见光下降解甲基橙溶液的影响。700 ℃下制备的衍生碳质材料的降解率为12.4 mg/g。光电化学测试结果表明,多孔g-C₃N₄衍生碳质材料的光生载流子密度、电荷分离和光电流(提高了5.4倍)均得到显著提高。因此,该简便、灵活方法为提高g-C₃N₄衍生碳质材料的吸附和光催化性能提供了一种有前景的、高效的途径。

Synthesis and Photocatalytic Performance of Catalytic Graphitization of g-C3N4 Carbonaceous Materials

The preparation methods for porous graphitic carbon materials have mostly employed a conventional two-step strategy, in which hydroxides act as the pore-forming agent and transition metal nitrates or chlorides as the graphitization catalyst. However, most of the reagents mentioned above are toxic and corrosive, and multi-step processes are time-consuming. In this work, a one-step strategy to synthesize porous graphitic g-C₃N₄-derived carbon materials was established, and its photocatalytic performance was studied. The g-C₃N₄ bulks were prepared by conventional thermal polycondensation approach from dicyandiamide. Potassium ferrate (K₂FeO₄) was utilized as both activating agent and catalyst to fulfil the synchronous carbonization and graphitization of g-C₃N₄, this method is less time-demanding, highly efficient and pollution-free, when compared with a conventional two-step strategy. The g-C₃N₄-derived carbon materials delivers not only significantly improved visible-light absorption but also greatly enhanced photocatalytic activity compared to pristine g-C₃N₄. The effect of g-C₃N₄-derived carbon materials with different graphitization temperature on the degradation of methyl orange (MO) solution under visible light was studied. The results indicate that the degradation rate of g-C₃N₄-derived carbon materials prepared at 700 ℃ is 12.4 mg/g. Photoelectrochemical measurements reveal that the porous graphitic samples exhibit improved carrier densities, charge separation, and photocurrent (a 5.4-fold increase) compared to that of the original g-C₃N₄. Consequently, this facile and versatile method could provide a promising and cost-effective approach to improve the absorption and photocatalysis performance of g-C₃N₄-derived carbonaceous materials.