泡沫状氮化碳的制备及其可见光分解水产氢性能

以三聚氰胺为前驱体,价格低廉、来源广泛的海泡石作为硬模板,制备出具有特殊空腔结构的泡沫状氮化碳。 通过透射电子显微镜、X射线粉末衍射、傅里叶变换红外光谱、N₂吸附-脱附、紫外可见漫反射光谱及荧光光谱等手段对样品的表面形貌和结构等物理性质进行表征,以光解水产氢性能考察其光催化活性,并通过电化学测试手段考察其光生电荷传输和分离情况。 结果表明,聚多巴胺能起到粘接剂作用,改善了前驱体与模板的结合,制备出的泡沫状氮化碳具有更大的比表面积;随模板用量增加,氮化碳的比表面积增大,当聚多巴胺改性海泡石与三聚氰胺质量比为2:1时,泡沬状氮化碳比表面积可达389.2 m²/g,其可见光产氢速率约为1061.87 μmol/(g·h),较体相氮化碳和未经多巴胺改性海泡石制备的氮化碳分别提高了7和2.6倍。 这表明大比表面积的泡沫状氮化碳为光催化反应提供了更多的活性位点,改善了多相光催化反应的传质扩散过程,提高了光生电子-空穴的分离效率,其特殊的空腔结构能有效地提高光的利用率,从而提高其光催化活性。

Foam-Like Graphitic Carbon Nitride: Synthesis and Visible-Light-Driven Photocatalytic Activity for Hydrogen Evolution

The foam-like graphitic carbon nitride(g-C₃N₄) was synthesized by using melamine as the raw material and cheap sepiolite as the hard template, respectively. The as-prepared samples were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), Fourier transform infrared(FT-IR) spectrometry, Brunauer-Emmett-Teller(BET) method, ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS), photoluminescence(PL) spectroscopy and electrochemical measurements, and the photocatalytic activity was evaluated by visible light driven hydrogen evolution. The results show that polydopamine can act as adhesives,which can improve the combined degree between the template and melamine, leading to the increase of the specific surface area of foam-like graphitic carbon nitride. Furthermore, the specific surface area of the obtained sample increases with the increase of polydopamine-modified sepiolite, when the mass ratio of polydopamine-modified sepiolite and melamine is 2:1, the specific surface area of the foam like g-C₃N₄ is as high as 389.2 m²/g and the visible light driven H₂ evolution rate can reach up to 1061.87 μmol/(g·h), which is ~7 times greater than that of bulk g-C₃N₄(151.24 μmol/(g·h)) and 2.6 times higher than that of g-C₃N₄ synthesized by unmodified sepiolite, respectively. This indicates that the foam-like g-C₃N₄ with a large surface area can provide more active sites and improve the diffusion process of multi-phase photocatalytic reaction, enhancing the separation efficiency of photogenerated electrons and holes. Additionally, the unique cavity structure can also effectively improve the utilization of light, leading to a significant improvement in the photocatalytic performance.