硅藻壁类储油地质构造的纳米孔层对气体的存储机理研究

Living diatoms consume 20% of global CO2. Their unique SiO2 cell walls (frustules) have attracted general interest to materials scientists, biologists, geologists, and oceanographers. It has long been believed that there are only three levels of hierarchical pore structures at a sub-micrometer resolution for these frustules. However, the fourth level, i.e., alternately packed dense/loose nanolayers that are topologically similar to the geological petroleum reservoirs, was found in frustules very recently. These structures can serve as CO2 buffers for diatoms, which can provide novel ideas to those fields as mentioned above. Nevertheless, as a study at its primary stage, lots of important mechanisms, e.g., the spatial structures of these new-found nanopores and the dynamic process for them to absorb gas, are yet to be understood. Hence, this project will characterize the structures of these fourth-level-pores, clarify their mechanisms for gas adsorption, and develop advanced materials based on these pores with high abilities to absorb gases. This work not only can expand the strategies for designing high-quality gas absorbents inspired by the frustules structures, but might also affect the classification criteria for diatom species as well. Moreover, it can provide a novel perspective for studying the diatom evolution and the changes in the concentration of atmospheric CO2.

硅藻通过光合作用消耗了全球约20%的温室气体CO2，其独特的SiO2细胞壁是材料、生命、地质、海洋等多学科领域所共同关注的研究热点。多年来，学术界普遍认为硅藻壁的跨尺度亚微米孔结构仅有三级，近期发现的硅藻壁类似储油地质构造的第四级结构——疏密相间的纳米孔层，及其所具有的CO2存储功能，突破了固有认识，为上述领域的研究提供了崭新思路。然而，硅藻壁第四级纳米孔层研究目前尚处起步阶段，其三维孔道结构、对气体吸附的动力学机制急需阐明。本项目针对上述关键科学问题，深入探索硅藻壁第四级纳米孔层的空间结构，揭示其吸附、存储CO2等气体的机理，并充分利用硅藻壁的天然纳米孔层结构开发高性能气体吸附材料。本工作不但可将基于硅藻壁结构的新材料设计从亚微米水平拓展到纳米水平，从而引发大量潜在应用，而且有可能影响到硅藻的现有分类准则，并为诸如不同地质年代里大气的CO2浓度变化、藻类的进化等重要研究提供全新途径。

2014年，项目组率先发现了硅藻壁的第四级孔结构—疏密相间的纳米孔堆垛层，并指出该结构可缓存水中的CO2并为光合作用提供原料，该观点挑战了目前学术界对水生藻类细胞壁功能和CO2浓缩机制的理解。本项目以掌握硅藻壁第四级孔的空间构造，揭示其吸附、存储CO2等气体的机理，充分利用硅藻壁的天然纳米孔层结构开发高性能功能材料为目标，研究了多类型硅藻壁微纳孔层的构型，建立了硅藻壁构型与功能基元的通用复合技术，创制了多种硅藻土功能复合材料并进行了相关机理研究及初步应用探索。项目组基于多种硅藻壁四级孔的空间结构建立了数据库，针对硅藻等生物构型与多材质、多形貌、跨尺度功能基元间缺乏通用复合方法的难点，提出并建立了两项复合新技术，开发了两种在海水淡化和光催化领域具有优异性能的新型硅藻土功能复合材料。本项目将基于硅藻壁构型的新材料设计从亚微米水平拓展到纳米水平，展示了利用硅藻壁构型创制新型高性能功能复合材料的重大前景。.通过本项目实施，共发表 SCI 论文 28 篇、核心期刊论文 2 篇、北大中文核心期刊论文3篇，申请国家发明专利3项，在国际上该研究领域里继续保持先发有利位置。培养了博士研究生 4 名、硕士研究生 1 名，形成了一支高水平、高效的研究团队。