光敏剂共价功能化石墨烯的电子传递和对光催化增强作用研究

Sensitizers functionalized graphene will be prepared by covalently bonding porphyrin-, phthalocyanine- or tris(2,2'-bipyridyl)ruthenium molecules, respectively, on the two-dimensional plane of graphene through 1,3-dipolar cycloaddition. The sensitizer covalently functionalized graphenes combine outstanding properties of the both moieties of the composite, i.e. exceptional optical and electronic properties of the organic sensitizers and nice properties of electron-acception and electron-transfer of graphene. Covalently functionalized graphene can be used as a novel photosensitizer as well as a two-dimentional conductive carrier to support metal nanoparticles or other useful components, forming novel photocatalytic materials. Under irradiation of light, excited electrons transfer from the sensitizer moiety to the metal nanoparticles through graphene. The molecular heterojunction existing in the nanocomposit enhances the separation efficiency of photoexcited carriers and reduces the possibility of charge recombination, enhancing the photocatalytic activity of the nanocomposite. By investigation of the photo-harvesting ability, the photoexcited electron transfer, the microscopic mechanism and photocatalytic enhancement of the sensitizers covalently functionalized graphene composite，the effective methods of tuning light-induced electron-transfer on the nanocomposite and the valuable references for developing the novel photocatalytic material for water splitting to produce hydrogen are expected to be developed.

用1,3-偶极环加成法,在石墨烯二维平面上引入与其通过化学键联接的卟啉类、酞菁类或联吡啶钌类光敏剂分子形成光敏剂共价功能化石墨烯。光敏剂共价功能化石墨烯既具有光敏剂分子独特的光、电性能也具有石墨烯优异的接受和传递电子性能。石墨烯经共价功能化后，既可作为一种新的光敏剂材料又可作为可传导电子的二维平面载体，承载金属纳米粒子或其它有用组分，形成新的具有光催化性能的光敏剂共价功能化石墨烯复合物。光照下，光敏剂分子上的激发电子经石墨烯传输至金属纳米粒子，由于分子异质结效应，光生电子回传几率降低，载流子分离效率提高。因而共价功能化石墨烯对光催化反应具有很好的增强效应。 通过研究光敏剂分子共价功能化石墨烯复合物的光捕获能力、光生电子转移规律、微观机制以及对光催化反应的增强作用，掌握有效的调控功能化石墨烯/纳米复合物上光生电子转移方法，为开发光催化分解水反应新材料提供有用的参考依据。

采用1,3-偶极环加成法、酰胺缩合等方法反应合成了金属酞菁、联吡啶钌络合物共价功能化石墨烯、金属酞菁共价功能化氮掺杂超小石墨烯量子点等有机敏化剂共价功能化石墨烯复合物，制备了硫化镉纳米粒子修饰的五氧化二铌纳米棒及其与氮掺杂石墨烯复合的三元复合物、氮掺杂亚孔Nb2O5、TiO纳米粒子功能化的氮掺杂石墨烯复合物等多种光催化剂。研究了光催化剂的结构和形貌、石墨烯上掺杂位点对负载物的作用、光激发下电子传递性能、光电化学性能和光催化分解水产氢（产氧）性能。.研究发现有机光敏剂分子功能化石墨烯后，复合物的光捕获范围可拓宽至可见光区，光生电子能够从光敏剂分子或半导体上经石墨烯传递至金属纳米粒子助催化剂上发生光催化反应。石墨烯作为电子接受体和传递体有效的增强了光生电荷分离效率。有机光敏剂分子共价功能化石墨烯的电子传递效率和光催化效率要远高于相应的非共价功能化石墨烯复合物。.通过研究光敏剂分子功能化石墨烯及半导体功能化石墨烯复合物的合成、光捕获能力、光生电子转移规律以及光催化作用，了解了光电子转移的微观机制和物理本质，为探索可望用于制备光电化学池光催化分解水制氢的光电极催化剂打下了良好的基础。