Cheng Long, Guo Yanan, Liu Quan, Liu Guozhen, Li Renhao, Chen Xi, Zeng Hui, Liu Gongping, Jin Wanqin
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, 30 Puzhu Road, Nanjing, 211816, P. R. China.
Adv Mater. 2022 Nov;34(44):e2206349. doi: 10.1002/adma.202206349. Epub 2022 Oct 3.
Membranes with nanochannels have exhibited great potential in molecular separations, while it remains a great challenge to separate molecules with very close physical properties and kinetic diameters (e.g., ethylene/ethane) owing to the lack of size-sieving property and specific affinity. Herein, a metal confined 2D sub-nanometer channel is reported to successfully discriminate ethylene over ethane via molecular recognition and sieving. Transition metal cations are paired with polyelectrolyte anions to achieve high dissociation activity, forming reversible complexation with ethylene. Aberration-corrected transmission electron microscopy observes that the metals with size of ≈2 nm are uniformly confined in graphene oxide (GO) interlayer channels with average height of ≈0.44 nm, thereby cooperating the size-sieving effect with a molecular recognition ability toward ethylene and stimulating its selective transport over ethane. The resulting ultrathin (≈60 nm) membrane exhibits superior ethylene/ethane separation performance far beyond the polymeric upper-bound. Density functional theory (DFT) and molecular dynamic simulations reveal that the metal@2D interlayer channel provides a molecular recognition pathway for selective gas transport. The proposed metal confined in 2D channel with molecular recognition and sieving properties would have broad application in other related fields such as single-atom catalysis, sensor and energy conversion.
具有纳米通道的膜在分子分离方面展现出了巨大潜力，然而，由于缺乏尺寸筛分特性和特异性亲和力，分离物理性质和动力学直径非常接近的分子（如乙烯/乙烷）仍然是一个巨大挑战。在此，据报道一种金属受限二维亚纳米通道通过分子识别和筛分成功地实现了乙烯与乙烷的区分。过渡金属阳离子与聚电解质阴离子配对以实现高解离活性，与乙烯形成可逆络合。像差校正透射电子显微镜观察到，尺寸约为2纳米的金属均匀地限制在平均高度约为0.44纳米的氧化石墨烯（GO）层间通道中，从而将尺寸筛分效应与对乙烯的分子识别能力相结合，并促进其对乙烷的选择性传输。所得的超薄（约60纳米）膜表现出优异的乙烯/乙烷分离性能，远远超过聚合物上限。密度泛函理论（DFT）和分子动力学模拟表明，金属@二维层间通道为选择性气体传输提供了分子识别途径。所提出的具有分子识别和筛分特性的二维通道受限金属在单原子催化、传感器和能量转换等其他相关领域将有广泛应用。
