Aqueous proton-selective conduction across two-dimensional graphyne

• Published in: Nature communications 2019-03, Vol.10 (1), p.1165-1165, Article 1165
• Main Authors: Shi, Le, Xu, Ao, Pan, Ding, Zhao, Tianshou
• Format: Article
• Language: English
• Subjects: 119/118; 639/301/299/893; 639/4077/4079/891; 639/638/563/981; Aqueous environments; Conduction; Crossovers; Energy; Fuel cells; Fuel technology; Graphene; Humanities and Social Sciences; Liquid fuels; Membranes; Methanol; multidisciplinary; Pore size; Porosity; Proton conduction; Protons; Science; Science (multidisciplinary); Simulation; Vacuum
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09151-8

The development of direct methanol fuel cells is hindered by the issue of methanol crossover across membranes, despite the remarkable features resulting from the use of liquid fuel. Here we investigate the proton-selective conduction behavior across 2D graphyne in an aqueous environment. The aqueous proton conduction mechanism transitions from bare proton penetration to a mixed vehicular and Grotthuss transportation when the side length of triangular graphyne pores increases to 0.95 nm. A further increase in the side length to 1.2 nm results in the formation of a patterned aqueous/vacuum interphase, enabling protons to be conducted through the water wires via Grotthuss mechanism with low energy barriers. More importantly, it is found that 2D graphyne with the side length of less than 1.45 nm can effectively block methanol crossover, suggesting that 2D graphyne with an appropriate pore size is an ideal material to achieve zero-crossover proton-selective membranes. Aqueous proton-selective membranes are vital for methanol fuel cells and flow batteries, but suffer from crossover issues. Here the authors use ab initio molecular dynamics simulations to show that graphyne is an ideal candidate for a proton-selective membrane that can be tailored for methanol impermeability