氧掺杂氮化碳纳米片的制备及其光解水制氢性能

Preparation and Photocatalytic Hydrogen Evolution from Water of Oxygen Doped Carbon Nitride Nanosheets

以草酸为氧源,二聚氰胺和尿素为原料,采用两步热聚合方式合成氧掺杂氮化碳纳米片催化剂(CNO)。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、X射线光电子能谱分析(XPS)、荧光光谱(PL)及电化学测试等技术对催化剂进行结构表征分析。在可见光照射下通过分解水制氢反应对CNO的光催化还原性能进行评价。结果表明,草酸中的O元素通过取代氮化碳三嗪环结构中N原子直接键合到sp2杂化碳上,形成O掺杂CNO。经O掺杂改性后的氮化碳具有良好的层状堆积结构,可见光吸收性明显提高,同时禁带宽度降低。O掺杂的引入加速了光生电子-空穴对的分离和传输,能大幅度提高氮化碳的光催化分解水制氢性能,在可见光照下达88.6μmol·h^-1,是未掺杂CN的3.91倍。

Oxygen-doped carbon nitride nanosheets catalyst (CNO) was synthesized by two-step thermal polymerization method using oxalic acid as oxygen source,melamine and urea as raw materials.X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM),ultraviolet-visible absorption spectroscopy (UV-Vis),X-ray photoelectron spectroscopy (XPS),fluorescence spectroscopy (PL),and electrochemical measurements were carried out to characterize and analyze the structures of catalysts.The photocatalytic reduction properties of CNO were tested by H2 production from water splitting under visible light irradiation.The results showed that O elements directly replaced N in the triazine ring structure and bonded to the sp2 hybridized carbon to form CNO.The CNO showed good layered structure,improved absorption of visible light,and lowered band gap.Due to the O doping,the separation and transmission of photogenerated electron-hole pairs were accelerated.Under visible light irradiation,the hydrogen generation rate from water by CNO was greatly enhanced and the evolution rate was up to 88.6 μmol·h^-1,which was 3.91 times as undoped CN.