Kinetic Control of Angstrom-Scale Porosity in 2D Lattices for Direct Scalable Synthesis of Atomically Thin Proton Exchange Membranes.
ACS Nano
; 16(10): 16003-16018, 2022 Oct 25.
Article
em En
| MEDLINE
| ID: mdl-36201748
ABSTRACT
Angstrom-scale pores introduced into atomically thin 2D materials offer transformative advances for proton exchange membranes in several energy applications. Here, we show that facile kinetic control of scalable chemical vapor deposition (CVD) can allow for direct formation of angstrom-scale proton-selective pores in monolayer graphene with significant hindrance to even small, hydrated ions (K+ diameter â¼6.6 Å) and gas molecules (H2 kinetic diameter â¼2.9 Å). We demonstrate centimeter-scale Nafion|Graphene|Nafion membranes with proton conductance â¼3.3-3.8 S cm-2 (graphene â¼12.7-24.6 S cm-2) and H+/K+ selectivity â¼6.2-44.2 with liquid electrolytes. The same membranes show proton conductance â¼4.6-4.8 S cm-2 (graphene â¼39.9-57.5 S cm-2) and extremely low H2 crossover â¼1.7 × 10-1 - 2.2 × 10-1 mA cm-2 (â¼0.4 V, â¼25 °C) with H2 gas feed. We rationalize our findings via a resistance-based transport model and introduce a stacking approach that leverages combinatorial effects of interdefect distance and interlayer transport to allow for Nafion|Graphene|Graphene|Nafion membranes with H+/K+ selectivity â¼86.1 (at 1 M) and record low H2 crossover current density â¼2.5 × 10-2 mA cm-2, up to â¼90% lower than state-of-the-art ionomer Nafion membranes â¼2.7 × 10-1 mA cm-2 under identical conditions, while still maintaining proton conductance â¼4.2 S cm-2 (graphene stack â¼20.8 S cm-2) comparable to that for Nafion of â¼5.2 S cm-2. Our experimental insights enable functional atomically thin high flux proton exchange membranes with minimal crossover.
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MEDLINE
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En
Ano de publicação:
2022
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Article