石墨烯-银类纳米复合材料的组装，机理及其可见光光催化性能研究

Environmental pollution is affecting human survival and development, photocatalysts, which can act as an green environmental protection agent, are proven to have great potentials in the field.Most traditional photocatalysts (such as TiO2) are not suitable for large-scal practical applications, due to their limited visible-light absorption and low quantum efficiency. It was found that many Ag-based photocatalysts showed obviously higher photocatalytic under visible-light irradiation than those traditional photocatalysts, thus Ag-based photocatalysts have recived extensive attentions and applied in various fields. In this research project, we will synthesize morphology and size controllable graphene -silver based (Ag3PO4, Ag2CO3, Ag2MoO4 etc.) nanocomposites with the methods of sonochemistry, photochemical and hydrothermal etc. and obtain distinct photochemical properties by carefully functionalizing the nanomaterials. We will combine the graphene with silver based nanomaterials by the techniques of in-situ growth, electrostatic adsorption,self-assembly and embedding, and investigate the influences of the reaction mechanism and synthesis conditions on the composite structure, diameter and the photocatalytic performance.Graphene nanosheets with good conductivity and large surface area could be used as an electron transfer channel to reduce the charge recombination, thus leading to the improved photoconversion ef?ciency of the photocatalytic materials. Besides, graphene can also increase the adsorbility of photocatalysts toward pollutants and extend the light absorption range of photocatalysts.Therefore, to develop a simple, low cost, recyclable and efficient graphene - silver based composite photocatalyst method is of significant importance.

环境污染影响着人类生存和发展,光催化剂作为一种绿色环保处理剂具有广阔的应用前景。传统光催化材料(如 TiO2)具有光响应区间窄和量子产率低的缺点，极大的限制了其实际应用。银类光催化剂具有可见光响应和量子产率较高等优点而受到广泛关注。本项目以超声化学、光化学、水热等方法合成石墨烯-银类(Ag3PO4 Ag2CO3 Ag2MoO4等)纳米复合材料，开展纳米材料功能化的研究，使之具有特殊的光化学性质；通过原位生长、静电吸附、自组装、包埋法等方法，石墨烯与银类纳米材料相结合，系统研究反应机理及合成条件对复合材料结构、粒径及其光催化性能的影响。石墨烯纳米片具有良好的导电性和大表面积，可作为电子传输信道，减少电荷复合，从而导致光催化材料光转换效率的改进。石墨烯还能提高光催化剂对污染物的吸附能力，并延长其光吸收范围。因此，开发一种简单、低成本、可循环利用且高效石墨烯-银类复合光催化剂的方法具有重要的意义

本研究利用超声化学方法将量子尺寸的银基材料（如：Ag3PO4 QDs、Ag2CrO4 QDs、Ag2CO3 QDs、AgCl QDs等）均匀地固定在氧化石墨烯表面，创立了超声-光联用技术，成功用超声辅助-光还原法制备了系列还原氧化石墨烯(RGO)-银基量子点的复合材料，对材料及其性能进行了表征及评价。以亚甲基蓝(MB)、罗丹明B(RhB)、四环素（TC）、环丙沙星（CIP）等为模拟污染物，对合成复合材料的催化性能进行了研究，同时探讨了光-超声、光-电的联用技术对污染物降解效果的影响。结果显示,复合材料的性能有显著提高。其中，2.3% RGO/Ag3PO4 QDs和0.5%RGO/Ag2CrO4 QDs对MB的光催化降解率分别达到97.5%（5min）和97.68%（60min）；1% RGO/Ag2CO3 QDs对TC的光、光-超降解率分别达到90%和97.3%（60min）；2% RGO/AgCl QDs对TC的光、光电降解率分别达到39.18%和85.2%（120min）；通过超声法制备棒状AgCO3纳米材料和分级AgCl材料，其对MB降解率分别达到99.4%（20min）和98.17%（40min）；通过阴离子交换法原位合成了5% β-Ag2MoO4/AgBr异质结材料，对RhB的降解率5min就达到98.4%；通过搅拌法合成2% RGO/AgCl球形材料，对TC的降解率90min达到80.6%；超声辅助阴离子交换合成AgCl0.5Br0.5 异质结材料，对CIP的光催化降解率120min达到65.5%。最终创立了一种简单、低成本、可行的“超声-光联用合成石墨烯-银基复合材料”绿色合成方法，从而提高了石墨烯-银基复合材料的光催化活性及稳定性。为石墨烯基复合材料的绿色可控合成工艺提供了有利的理论依据。