二维超薄g-C3N4的合成与表面功能化组装对提高光催化性能的研究

Two-dimensional ultrathin g-C3N4 has attracted intensive research interests in field of the solid-state chemistry,due to its excellent characteristics of enviromental friendly,earth-abundent building elements and photocatalytic activity. However, production yield of the liquid exfoliation of layerd g-C3N4 is poor,and size of the obtained ultrathin g-C3N4 nanosheets is small.The dispersible small sized nanosheets as photocatalysts are difficult to be recovered. Furthermore,the flexible surface and the heterocyclic nitrogens in the framework are not functionally utilized. Towards these challenges,we attempt to employ the strategies of employing the synthesis of solid-state high temperature thermal expansion, fabricating morphologies of the surface wrapping and the encapsulation by assembly,and the supermolecular forces between the nitrogens and the Fe(III) complex to obtain large sized ultrathin g-C3N4 nanosheets on large-scale with high yield, to integrating space-seperated magnetic components and photocatalytic components on the double interfaces of ultrathin g-C3N4 nanosheets, and coupling the photocatalysis and Fenton reaction. In this proposal,we will investigate the key factors to control the thermal expansion and its effects on the morphology,structure and electrical conductivity of ultrathin g-C3N4 nanosheets. And,we should also study the solution assembly process and electrospun process to determine the key factors, and elucidate the contributions of these functional components on improving the photocatalytic performances. Finally, we need to examine the effects of ligands, pH and hydroperoxide on the coupling of the photocatalysis and Fenton effect. Through these investigations, we aim to obtain solid-state thermal expansion sythesis techniques and magnetically recyclable two-dimensional g-C3N4 integration photocatalysis systems with high photocatalytic activity and stability, and coupling Fenton effects.

二维超薄g-C3N4具有环境友好、组成元素含量丰富和光催化活性的优点，成为无机固态化学研究的焦点，但液相剥离层状g-C3N4的产率低、尺寸小，分散性好、光催化应用难于回收且二维超薄柔性表面和氮杂环没有功能化利用。针对以上问题，本项目拟采用固相高温热膨胀合成技术，包裹和包埋形貌组装及氮杂环对Fe(III)配合物超分子作用的策略来规模化高产率大尺寸合成，在柔性内外表面空间分离地集成磁性和光催化单元及耦合光催化-芬顿效应。研究热膨胀合成关键因素和机理及对形貌、结构和电学性质的影响；研究溶液法组装和静电纺丝组装的关键因素及功能单元对光催化性能的贡献；研究光催化-芬顿耦合过程中配体、过氧化氢和pH的影响，从而获得大尺寸高产率的固相热膨胀合成技术和磁性可回收、光催化活性高且循环稳定的二维超薄g-C3N4集成光催化材料体系和耦合新途径。

石墨相氮化碳（g-C3N4）材料具有稳定性高、廉价易得、环境友好、可见光响应等特点，使其成为光催化领域的研究热点之一。本项目主要采用高温热膨胀技术热解前驱体，通过调控和优化制备条件，获得具有不同形貌和微结构的超薄g-C3N4及其修饰材料，深入探讨影响光催化降解及光解水产氢活性的诸多因素。. 通过引入Fe(III)化合物修饰实现了g-C3N4材料的表面功能化。在模拟可见光或太阳光照射下，Fe(III)-羧酸盐修饰的g-C3N4材料和二茂铁鎓离子/g-C3N4与H2O2构成的Fenton体系，对罗丹明B或甲基橙染料表现出了优异的降解效果和循环稳定性；通过在g-C3N4缺陷表面组装杂多酸簇活性位点，构筑了FePW4簇-g-C3N4杂化材料，在降解有机染料方面显示出高活性及稳定性，放大实验表明该催化剂具有很好的实际应用可行性。. 研究了材料形貌、孔分布、缺陷等微结构和界面因素对g-C3N4光催化产氢性能的影响。褶皱形貌中空洞的存在增强了电荷分离效率，减少了电子-空穴对的复合几率，有利于Pt/g-C3N4光解水产氢活性的提高；g-C3N4中混合相结构的存在，使材料的比表面积增大、聚集程度增加，可以增强材料的光解水产氢活性。分别以尿素、硫脲和三聚氰胺等原作为前驱体热解得到g-C3N4材料，其中蜂窝状结构U-g-C3N4的光解水产氢活性最好，约为另两种g-C3N4材料活性的17倍；引入氯化铵和草酸铵对热解产物g-C3N4的形貌、孔结构、比表面积及活性位点等有很大影响，其中活性位点在光解水产氢过程中起着重要作用。 . 掌握了制备高产量g-C3N4二维材料新技术。探讨了载铂g-C3N4催化剂光解水产氢时的光热协同催化作用，光解水体系自身温度升高时的产氢活性明显高于控温（约10oC）时的速率，产氢速率提高约6倍；对牺牲剂三乙醇胺发生聚合的条件和聚合方式进行了分析。. 本项目研究加深了对g-C3N4表面形态、微结构和活性位点等的认知，筛选出光催化活性高并可循环使用的二维超薄g-C3N4及其修饰材料，在g-C3N4光催化性能研究领域具有重要的学术价值，也为g-C3N4材料的规模化制备及实际应用提供了依据。