Nanocrack-regulated self-humidifying membranes.
The regulation of water content in polymeric membranes is important in a number of applications, such as reverse electrodialysis and proton-exchange fuel-cell membranes. External thermal and water management systems add both mass and size to systems, and so intrinsic mechanisms of retaining water and maintaining ionic transport in such membranes are particularly important for applications where small system size is important. For example, in proton-exchange membrane fuel cells, where water retention in the membrane is crucial for efficient transport of hydrated ions, by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions. Here we report an alternative solution that does not rely on external regulation of water supply or high temperatures. Water content in hydrocarbon polymer membranes is regulated through nanometre-scale cracks ('nanocracks') in a hydrophobic surface coating. These cracks work as nanoscale valves to retard water desorption and to maintain ion conductivity in the membrane on dehumidification. Hydrocarbon fuel-cell membranes with surface nanocrack coatings operated at intermediate temperatures show improved electrochemical performance, and coated reverse-electrodialysis membranes show enhanced ionic selectivity with low bulk resistance.
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Chi Hoon
CH
Park
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
So Young
SY
Lee
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Doo Sung
DS
Hwang
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Dong Won
DW
Shin
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Doo Hee
DH
Cho
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Kang Hyuck
KH
Lee
Department of Life Science, College of Natural Science, Hanyang University, Seoul 133-791, South Korea.
Tae-Woo
TW
Kim
Department of Life Science, College of Natural Science, Hanyang University, Seoul 133-791, South Korea.
Tae-Wuk
TW
Kim
School of Mechanical Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Mokwon
M
Lee
School of Mechanical Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Deok-Soo
DS
Kim
Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, Victoria 3168, Australia.
Cara M
CM
Doherty
Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, Victoria 3168, Australia.
Aaron W
AW
Thornton
Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, Victoria 3168, Australia.
Anita J
AJ
Hill
State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China.|Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
Michael D
MD
Guiver
Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea.
Young Moo
YM
Lee
D040761:Biomimetic Materials / Q000737:chemistry; D032701:Biomimetics; D029421:Cactaceae / Q000378:metabolism; D003890:Desiccation; D003956:Dialysis; D004563:Electrochemistry; D006813:Humidity; D057927:Hydrophobic and Hydrophilic Interactions; D008567:Membranes, Artificial; D036103:Nanotechnology; D054046:Plant Stomata / Q000378:metabolism; D011108:Polymers / Q000737:chemistry*; D011522:Protons; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000032:analysis*
D008567:Membranes, Artificial; D011108:Polymers; D011522:Protons; D014867:Water