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Centimeter-scale gas-sieving nanoporous single-layer graphene membrane
Journal of Membrane Science ( IF 9.5 ) Pub Date : 2021-01-01 , DOI: 10.1016/j.memsci.2020.118745 Wan-Chi Lee , Luc Bondaz , Shiqi Huang , Guangwei He , Mostapha Dakhchoune , Kumar Varoon Agrawal
Journal of Membrane Science ( IF 9.5 ) Pub Date : 2021-01-01 , DOI: 10.1016/j.memsci.2020.118745 Wan-Chi Lee , Luc Bondaz , Shiqi Huang , Guangwei He , Mostapha Dakhchoune , Kumar Varoon Agrawal
Abstract High-permeance, molecular-sieving, nanoporous single-layer graphene (NSLG) membranes are highly promising for gas separation. However, the formation of cracks during the transfer of NSLG to a low-cost porous support is difficult to avoid. These cracks are detrimental to gas selectivity, and therefore, make the scale-up of the gas-sieving NSLG membranes challenging. To mitigate the crack formation on low-cost macroporous supports, herein, we demonstrate mechanical reinforcement of the graphene film with a two-layer composite carbon film. The bottom layer of the composite film is a 100-nm-thick block-copolymer film derived nanoporous carbon (NPC) film with a pore size of 20–30 nm. This layer makes an intimate contact with NSLG and prevents generation of crack. However, the NPC film by itself is not robust enough to cover the rough surface of low-cost macroporous supports and tends to generate occasional cracks. This is prevented by spin-coating a 500-nm-thick multi-walled carbon nanotube (MWNT) film, hosting pore size of 200–300 nm, on top of the NPC film. This imparts enough mechanical strength of NSLG/NPC film to be successfully suspended on a low-cost, macroporous, nonwoven metal wire mesh on a centimeter-scale while completely avoiding cracks. As a result, H2/CH4 and H2/CO2 selectivities of 11–23 and 5–8, respectively, higher than the corresponding Knudsen selectivities of 2.8 and 4.7, respectively, are obtained from the centimeter-scale NSLG membranes. The reinforced membranes are mechanically robust and can successfully withstand transmembrane pressure difference of 4 bar. When the MWNT film is directly coated on NSLG without using the intermediate NPC layer, the gas sieving behavior is not observed, perhaps due to the development of nanoscale cracks. This underlines the crucial role of the hierarchical pore structure in the composite carbon film in realizing the gas-sieving graphene membranes.
中文翻译:
厘米级气体筛分纳米多孔单层石墨烯膜
摘要 高渗透性、分子筛分、纳米多孔单层石墨烯 (NSLG) 膜在气体分离方面非常有前景。然而,在将 NSLG 转移到低成本多孔载体的过程中,裂缝的形成是难以避免的。这些裂缝不利于气体选择性,因此使气体筛分 NSLG 膜的放大具有挑战性。为了减轻低成本大孔载体上的裂纹形成,在此,我们展示了用两层复合碳膜对石墨烯膜进行机械增强。复合膜的底层是 100 nm 厚的嵌段共聚物膜衍生的纳米多孔碳 (NPC) 膜,孔径为 20-30 nm。该层与 NSLG 紧密接触并防止裂纹的产生。然而,NPC 薄膜本身不够坚固,无法覆盖低成本大孔支撑的粗糙表面,并且往往会产生偶尔的裂缝。这可以通过在 NPC 膜上旋涂 500 nm 厚的多壁碳纳米管 (MWNT) 膜来防止,该膜具有 200-300 nm 的孔径。这赋予 NSLG/NPC 薄膜足够的机械强度,使其成功悬浮在厘米级的低成本、大孔、非织造金属丝网上,同时完全避免裂缝。因此,从厘米级 NSLG 膜获得的 H2/CH4 和 H2/CO2 选择性分别为 11-23 和 5-8,分别高于相应的 Knudsen 选择性 2.8 和 4.7。增强膜具有机械强度,可以成功承受 4 巴的跨膜压差。当 MWNT 薄膜直接涂覆在 NSLG 上而不使用中间 NPC 层时,没有观察到气体筛分行为,这可能是由于纳米级裂纹的发展。这强调了复合碳膜中的分级孔结构在实现气体筛分石墨烯膜中的关键作用。
更新日期:2021-01-01
中文翻译:
厘米级气体筛分纳米多孔单层石墨烯膜
摘要 高渗透性、分子筛分、纳米多孔单层石墨烯 (NSLG) 膜在气体分离方面非常有前景。然而,在将 NSLG 转移到低成本多孔载体的过程中,裂缝的形成是难以避免的。这些裂缝不利于气体选择性,因此使气体筛分 NSLG 膜的放大具有挑战性。为了减轻低成本大孔载体上的裂纹形成,在此,我们展示了用两层复合碳膜对石墨烯膜进行机械增强。复合膜的底层是 100 nm 厚的嵌段共聚物膜衍生的纳米多孔碳 (NPC) 膜,孔径为 20-30 nm。该层与 NSLG 紧密接触并防止裂纹的产生。然而,NPC 薄膜本身不够坚固,无法覆盖低成本大孔支撑的粗糙表面,并且往往会产生偶尔的裂缝。这可以通过在 NPC 膜上旋涂 500 nm 厚的多壁碳纳米管 (MWNT) 膜来防止,该膜具有 200-300 nm 的孔径。这赋予 NSLG/NPC 薄膜足够的机械强度,使其成功悬浮在厘米级的低成本、大孔、非织造金属丝网上,同时完全避免裂缝。因此,从厘米级 NSLG 膜获得的 H2/CH4 和 H2/CO2 选择性分别为 11-23 和 5-8,分别高于相应的 Knudsen 选择性 2.8 和 4.7。增强膜具有机械强度,可以成功承受 4 巴的跨膜压差。当 MWNT 薄膜直接涂覆在 NSLG 上而不使用中间 NPC 层时,没有观察到气体筛分行为,这可能是由于纳米级裂纹的发展。这强调了复合碳膜中的分级孔结构在实现气体筛分石墨烯膜中的关键作用。