Xu Jiyu, Jiang Hongyu, Shen Yutian, Li Xin-Zheng, Wang E G, Meng Sheng
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
Nat Commun. 2019 Sep 3;10(1):3971. doi: 10.1038/s41467-019-11899-y.
Molecular sieving is of great importance to proton exchange in fuel cells, water desalination, and gas separation. Two-dimensional crystals emerge as superior materials showing desirable molecular permeability and selectivity. Here we demonstrate that a graphdiyne membrane, an experimentally fabricated member in the graphyne family, shows superior proton conductivity and perfect selectivity thanks to its intrinsic nanomesh structure. The trans-membrane hydrogen bonds across graphdiyne serve as ideal channels for proton transport in Grotthuss mechanism. The free energy barrier for proton transfer across graphdiyne is ~2.4 kJ mol, nearly identical to that in bulk water (2.1 kJ mol), enabling "transparent" proton transport at room temperature. This results in a proton conductivity of 0.6 S cm for graphdiyne, four orders of magnitude greater than graphene. Considering its ultimate pore size of 0.55 nm, graphdiyne membrane blocks soluble fuel molecules and exhibits superior proton selectivity. These advantages endow graphdiyne a great potential as proton exchange material.
分子筛在燃料电池中的质子交换、水脱盐和气体分离方面具有重要意义。二维晶体作为具有理想分子渗透性和选择性的优异材料而出现。在这里，我们证明了石墨炔膜，一种在石墨炔家族中通过实验制备的成员，由于其固有的纳米网结构而表现出优异的质子传导性和完美的选择性。跨越石墨炔的跨膜氢键作为质子在Grotthuss机制中传输的理想通道。质子穿过石墨炔的自由能垒约为2.4kJ/mol，与 bulk water（2.1kJ/mol）几乎相同，能够在室温下实现“透明”质子传输。这导致石墨炔的质子传导率为0.6S/cm，比石墨烯高四个数量级。考虑到其最终孔径为0.55nm，石墨炔膜可阻挡可溶性燃料分子并表现出优异的质子选择性。这些优点使石墨炔作为质子交换材料具有巨大潜力。
