Department of Mechanical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
ACS Nano. 2017 Oct 24;11(10):10042-10052. doi: 10.1021/acsnano.7b04299. Epub 2017 Oct 10.
Nanoporous graphene has the potential to advance membrane separations by offering high selectivity with minimal resistance to flow, but how mass transport depends on the structure of pores in this atomically thin membrane is poorly understood. Here, we investigate the relationship between tunable pore creation using ion bombardment and oxygen plasma etching, the resulting pore size distributions, and the consequent water and solute transport. Through tuning of the pore creation process, we demonstrate nanofiltration membranes that reject small molecules but offer high permeance to water or monovalent ions. Theoretical multiscale modeling of transport across the membranes reveals a disproportionate contribution of large pores to osmotic water flux and diffusive solute transport and captures the observed trends in transport measurements except for the smallest pores. This work provides insights into the effects of graphene pore size distribution and support layer on transport and presents a framework for designing atomically thin membranes.
介孔石墨烯具有提供高选择性和最小流动阻力的潜力，有望推进膜分离，但这种原子级薄膜的孔结构如何影响传质仍知之甚少。在这里，我们研究了使用离子轰击和氧等离子体刻蚀来实现可调孔创建的关系，以及由此产生的孔径分布，以及随之而来的水和溶质传输。通过调整孔的创建过程，我们展示了纳滤膜，它可以排斥小分子，但对水或单价离子具有高渗透性。通过对膜内传输的多尺度理论建模，我们发现大孔对渗透压水通量和扩散溶质传输的贡献不成比例，并捕捉到了传输测量中的观察到的趋势，除了最小的孔。这项工作深入了解了石墨烯孔尺寸分布和支撑层对传输的影响，并为设计原子级薄膜提供了框架。
