US EPA

5161677 

Journal Article 

Ultrafast proton transport in sub-1-nm diameter carbon nanotube porins 

Tunuguntla, RH; Allen, FI; Kim, K; Belliveau, A; Noy, A 

2016 

1 

Nature Nanotechnology
ISSN: 1748-3387
EISSN: 1748-3395 

11 

7 

639-644 

English 

27043198 

10.1038/nnano.2016.43 

WOS:000379506600016 

Proton transport plays an important role in many biological processes due to the ability of protons to rapidly translocate along chains of hydrogen-bonded water molecules. Molecular dynamics simulations have predicted that confinement in hydrophobic nanochannels should enhance the rate of proton transport. Here, we show that 0.8-nm-diameter carbon nanotube porins, which promote the formation of one-dimensional water wires, can support proton transport rates exceeding those of bulk water by an order of magnitude. The transport rates in these narrow nanotube pores also exceed those of biological channels and Nafion. With larger 1.5-nm-diameter nanotube porins, proton transport rates comparable to bulk water are observed. We also show that the proton conductance of these channels can be modulated by the presence of Ca(2+) ions. Our results illustrate the potential of small-diameter carbon nanotube porins as a proton conductor material and suggest that strong spatial confinement is a key factor in enabling efficient proton transport.