Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States of America.
Nanotechnology. 2017 May 5;28(18):184003. doi: 10.1088/1361-6528/aa680f. Epub 2017 Mar 21.
Graphene membranes have the potential to exceed the permeance and selectivity limits of conventional gas separation membranes. Realizing this potential in practical systems relies on overcoming numerous scalability challenges, such as isolating or sealing permeable defects in macroscopic areas of graphene that can compromise performance and developing methods to create high densities of selective pores over large areas. This study focuses on a centimeter-scale membrane design, where leakage is reduced by substrate selection, permeable polymer film coating, and stacking of three independent layers of graphene, while (selective) pores are created by high density ion bombardment. The three-layer graphene provides high resistance to gas flow, which decreases with ion bombardment and results in selectivity consistent with Knudsen effusion. The results suggest that the permeable pores created in three layer graphene were larger than those required for molecular sieving and that designs based on single layer graphene may lend themselves more easily to molecular sieving of gases.
石墨烯膜具有超越传统气体分离膜渗透率和选择性极限的潜力。要在实际系统中实现这一潜力，需要克服许多可扩展性挑战，例如在宏观石墨烯区域中隔离或密封可能影响性能的可渗透缺陷，并开发在大面积上形成高密度选择性孔的方法。本研究专注于厘米级膜设计，通过选择衬底、涂覆可渗透聚合物膜和堆叠三层独立石墨烯来减少泄漏，同时通过高密度离子轰击来创建（选择性）孔。三层石墨烯提供了对气体流动的高阻力，随着离子轰击的进行阻力会降低，从而导致与克努森扩散一致的选择性。结果表明，在三层石墨烯中形成的可渗透孔大于分子筛所需的孔，并且基于单层石墨烯的设计可能更容易实现气体的分子筛分离。
