花状二维氮化碳在模拟太阳光下光催化降解水中磺胺氯哒嗪机理研究

Photocatalytic Degradation of Sulfachloropyridazine in Water by Flower-like 2D Carbon Nitride Under Simulated Solar Light

以三聚氰胺和三聚氰酸为主要原料,在二甲基亚砜中通过自组装过程形成超分子作为前驱体,再进行热缩聚制备了花状形貌的二维氮化碳光催化材料。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和光电化学等对材料进行了系统表征,结果表明所制备的光催化材料为类石墨相的氮化碳(g-C_(3)N_(4),SCN)。且相比较于热缩聚法合成的传统体相的氮化碳,SCN由于其超薄、均匀的结构组成,具有更高的光吸收能力和更低的禁带宽度(E_(g))。另外通过密度泛函理论(DFT)计算,对SCN的光催化激发过程进行了深度机理分析,发现材料独特的超薄氮化碳片和孔道结构抑制了光激发过程后电子-空穴对的复合。以废水中常见的活性药物类污染物磺胺氯哒嗪(SCP)为目标污染物,在模拟太阳光的条件下照射45 min后,目标污染物的去除率为100%,且降解的准一级反应动力学常数(k=0.085 min^(-1))约为体相氮化碳的两倍。本研究为可应用于高效制药废水污染净化的光催化系统的开发提供了理论指导,也可为新型光催化材料的开发提供借鉴。

Supermolecules were prepared using melamine and cyanuric acid as precursors through self-assembly process in dimethyl sulfoxide,which were then undertaken thermal polycondensation reaction to synthesize a two-dimensional(2D)photocatalyst with flower-like morphology.Various characterizations,including scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and photoelectrochemical measurements,indicate that the fabricated photocatalyst is graphitic carbon nitride(g-C_(3)N_(4),SCN).In addition,compared with the bulk g-C_(3)N_(4)prepared by traditional thermal polycondensation method,SCN exhibites a higher light absorption capability and lower bandgap due to its ultrathin and uniform structure composition.Moreover,density functional theory(DFT)calculation deeply reveals the mechanism of the photocatalytic reactions on SCN.The unique ultrathin carbon nitride sheet and channel structure of SCN can suppress the recombination rate of electron-hole pairs.Sulfachloropyridazine(SCP),a common active pharmaceutical pollutant in wastewater,was taken as the target pollutant in this study.After 45 min irradiation under simulated solar light by SCN,the removal efficiency of SCP reaches up to 100%,and the pseudo first-order kinetic constant(k=0.085 min^(-1))of SCP degradation is about twice that of bulk g-C_(3)N_(4).This study provides a theoretical guidance for development of photocatalysis technology which can be applied to the purification of pharmaceuticals contaminated wastewater,and also provides a reference for development of new photocatalysts.