以尿素(CO(NH2)2)和磷酸氢二铵((NH4)2HPO4)作为原料,通过热聚合法制备了磷(P)掺杂石墨相氮化碳(g-C3N4)材料(P-CN).通过X射线衍射、红外光谱、X射线光电子谱、扫描电子显微镜、透射电子显微镜、紫外可见漫反射光谱和N2吸附-脱附对样品进行了表面形貌及结构表征,通过对罗丹明B(RhB)的降解实验,研究了样品的可见光催化性能,对其催化机理进行了分析.结果表明,合成过程中磷原子的掺杂会取代g-C3N4中的C原子,从而改变g-C3N4的表面形貌和电子结构.在可见光条件下,P-CN材料表现出优异的光催化性能,其对RhB的降解速率明显优于纯氮化碳.其中3％P-CN样品催化活性最高,反应30 min时,RhB降解率达到96.8％.分析认为,P原子对g-C3N4中的C原子的取代使P-CN样品表面处于富电子状态,并导致P-CN样品导带位置升高,光电子还原性增强.这些电子与水中的溶解氧形成超氧自由基(·O2-),从而使得光催化性能显著提高.
A series of P-doped g-C3N4 (P-CN) samples were prepared using urea (CO(NH2)2) and diammonium hydrogen phosphate ((NH4)2HPO4) as raw materials by a simple thermal condensation method.The surface morphologies and structures of the as-prepared samples were characterized by X-ray diffraction (XRD),fourier transform infrared spectroscope (FT-IR),X-ray photoelectron spectroscope(XPS),scanning electron microscope (SEM),transmission electron microscope (TEM),UV-Vis diffuse reflection spectra (UV-Vis DRS) and N2 adsorption-desorption isotherms,respectively.The visible-light photocatalytic property was demonstrated for photodegradation of Rhodamine (RhB) solution,and the photocatalytic mechanism for the P-CN samples under visible-light was tentatively proposed.The corresponding results indicate that C atoms in g-C3N4 are replaced by P atoms,which modifies the surface morphologies and electronic structures.The as-prepared P-CN samples show remarkably higher photocatalytic efficiency than pure g-C3N4 for RhB degradation under visible-light irradiation.3％P-CN sample demonstrates the highest photocatalyric activity,which degrades 96.8％ RhB after reaction for 30 min.The replacement of P to C atoms in g-C3N4 makes the surface of P-CN in an electron-rich state.Furthermore,the research indicates the conduction band of P-CN shifts to more negative values,which improves the reduction performance of photoelectron.The electrons in conduction band of P-CN reduce O2 to ·O2-in the reaction system,so that the photocatalytic property are improved significantly.
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