3D石墨烯/纳米Pd宏观体相材料的生物制备及机制研究

As a new material, Pd nanoparticles (NPs) functionalized 3D graphene has a wide range of application in industry catalysis field. However, serious environment pollution resulted from in situ reduction assembly process (chemical reduction of GO and Pd(II), the most promising strategy) hindered its commercial application and became the bottleneck for this kind of materials. Bioreduction of GO and Pd(II) by bacteria holds great promise for green synthesis of nanomaterial. Thus, there are no reports about 3D graphene-functionalized composite materials by microbial reduction assembly. We found that graphene hydrogels were successfully prepared through the bioreduction of GO using Shewanella oneidensis MR-1. In this project, biosynthesis of 3D graphene/Pd NPs macro bulk material will be studied in detail. The co-reduction biochemical pathway of GO and Pd(II) will be analyzed. In order to reveal assembly mechanism of 3D graphene/Pd NPs macro bulk material, the critical factor involving Pd crystal nucleation and growth process will be studied. On this base, new rational strategy for crystal size, pattern and spatial distribution of Pd NPs will be proposed and carried out. This project will provide new understanding in GO and Pd(II) co-bio reduction, and will get innovative preparation technology, which should be valuable for solving the key bottlencks and promoting the sustainable development of graphene industry.

纳米Pd功能化的3D石墨烯是具有广泛工业应用前景的新兴催化材料。但是，高污染、高能耗的化学还原组装制备过程已成为该材料实际应用的关键瓶颈。生物还原是一种清洁生产新技术，但目前仍未有关于生物还原组装3D石墨烯复合功能材料的报道。我们前期已发现希瓦氏菌可生物还原氧化石墨烯（GO）并自组装形成石墨烯水凝胶。据此，本项目以3D石墨烯/纳米Pd宏观体相材料的生物组装为切入点，系统探讨影响Pd晶体成核和生长过程的关键因素；解析GO和Pd(II) 共还原的生化途径；揭示3D石墨烯/纳米Pd宏观体相材料的组装机理；在此基础上，探索纳米Pd颗粒晶型、尺寸、空间分布的调控策略，构筑高催化活性的3D石墨烯/纳米Pd宏观体相材料。该研究将有助于建立GO和Pd(II)生物共还原的理论，实现3D石墨烯复合功能材料的生物制备，为突破3D石墨烯复合功能材料制备的关键瓶颈、促进石墨烯工业的可持续发展提供新思路和新方法。

纳米Pd功能化的3D石墨烯是具有广泛工业应用前景的新兴催化材料。但是，高污染、高能耗的化学还原组装制备过程已成为该材料实际应用的关键瓶颈。目前微生物系统已成为一种生产低成本、绿色环保的新一代纳米材料的很有发展前景的途经。本项目通过对Shewanella oneidensis MR-1对GO和Pd(II)共还原合成过程研究，实现3D石墨烯@纳米Pd（3D Bio-rGO@Pd）复合功能材料的生物合成。同时，解析Shewanella oneidensis MR-1生物共还原GO和Pd(II)的机制。实验结果表明，Shewanella oneidensis MR-1相关蛋白和酶类调控，mtr的电子传递途径与3D Bio-rGO@Pd的合成息息相关，其中mtrB和CymA蛋白具有决定性作用。另外，氢化酶的存在与否不影响3D Bio-rGO@Pd的合成。在实践应用环节。首先，我们尝试了Bio-rGO@Pd对不同浓度的Cr(VI)还原降解消除，实验发现rGO和Pd纳米颗粒两者具有协同还原降解Cr(VI)的效果；进一步，经过简单的热解处理，Bio-rGO@Pd便成为具有良好ORR活性的催化剂；接着，我们构建高活性石墨烯水凝胶电极（3D Bio-rGO），促进微生物至电极间的EET高效传递，实现微生物燃料电池（MFCs）免接种产电菌直接启动；最后，我们将3D Bio-rGO@Pd构建固定床催化系统，用于4-硝基苯酚的还原。这种递进式研究方法充分挖掘出了这种利用细菌共还原GO和Pd(II)的优势，具有重大研究意义，为突破3D石墨烯复合功能材料的关键瓶颈和促进石墨烯工业的可持续发展提供新思路和新方法。