Carbon has emerged as a unique material in nanofluidics, with reports of fast water transport, molecular ion separation and efficient osmotic energy conversion. Many of these phenomena still await proper rationalization due to the lack of fundamental understanding of nanoscale ionic transport, which can only be achieved in controlled environments. Here we develop the fabrication of ‘activated’ two-dimensional carbon nanochannels. Compared with nanoconduits with ‘pristine’ graphite walls, this enables the investigation of nanoscale ionic transport in great detail. We show that activated carbon nanochannels outperform pristine channels by orders of magnitude in terms of surface electrification, ionic conductance, streaming current and (epi-)osmotic currents. A detailed theoretical framework enables us to attribute the enhanced ionic transport across activated carbon nanochannels to an optimal combination of high surface charge and low friction. Furthermore, this demonstrates the unique potential of activated carbon for energy harvesting from salinity gradients with single-pore power density across activated carbon nanochannels, reaching hundreds of kilowatts per square metre, surpassing alternative nanomaterials.
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Bocquet, L. Nanofluidics coming of age. Nat. Mater. 19, 254–256 (2020).
Faucher, S. et al. Critical knowledge gaps in mass transport through single-digit nanopores: a review and perspective. J Phys. Chem. C 123, 21309–21326 (2019).
Kavokine, N., Netz, R. & Bocquet, L. Fluids at the nanoscale: from continuum to subcontinuum transport. Annu. Rev. Fluid Mech. 53, 377–410 (2021).
Radha, B. et al. Molecular transport through capillaries made with atomic-scale precision. Nature 538, 222–225 (2016).
Nair, R. R. et al. Unimpeded permeation of water through helium-leak-tight graphene-based membranes. Science 335, 442–444 (2012).
Ji, J. et al. Osmotic power generation with positively and negatively charged 2D nanofluidic membrane pairs. Adv. Funct. Mater. 27, 1603623 (2017).
Jijo, A. et al. Tunable sieving of ions using graphene oxide membranes. Nat. Nanotechnol. 12, 546 (2017).
Yang, Q. et al. Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation. Nat. Mater. 16, 1198–1202 (2017).
Quan, X. et al. Fast water transport in graphene nanofluidic channels. Nat. Nanotechnol. 13, 238–245 (2018).
Ghanbari, H. & Esfandiar, A. Ion transport through graphene oxide fibers as promising candidate for blue energy harvesting. Carbon 165, 267–274 (2020).
Liu, X. et al. Power generation by reverse electrodialysis in a single-layer nanoporous membrane made from core–rim polycyclic aromatic hydrocarbons. Nat. Nanotechnol. 15, 307–312 (2020).
Salanne, M. et al. Efficient storage mechanisms for building better supercapacitors. Nat. Energy 1, 16070 (2016).
Siria, A., Bocquet, M.-L. & Bocquet, L. New avenues for the large-scale harvesting of blue energy. Nat. Rev. Chem. 1, 0091 (2017).
Macha, M., Marion, S., Nandigana, V. V. & Radenovic, A. 2D materials as an emerging platform for nanopore-based power generation. Nat. Rev. Mater. 4, 588–605 (2019).
Mouhat, F., Coudert, F. X. & Bocquet, M.-L. Structure and chemistry of graphene oxide in liquid water from first principles. Nat. Commun. 11, 1566 (2020).
Mouterde, T. et al. Molecular streaming and its voltage control in ångström-scale channels. Nature 567, 87–90 (2019).
Ferrari, A. C. & Robertson, J. Interpretation of Raman spectra of disordered and amorphous carbon. Phys. Rev. B 61, 14095 (2000).
Dresselhaus, M. S., Jorio, A. & Saito, R. Characterizing graphene, graphite, and carbon nanotubes by Raman spectroscopy. Annu. Rev. Condens. Matter Phys. 1, 89–10 (2010).
Nakhara, M. & Sanada, Y. Modification of pyrolytic graphite surface with plasma irradiation. J. Mater. Sci. 1, 1327–1333 (1993).
Thiele, C. et al. Electron-beam-induced direct etching of graphene. Carbon 64, 84–91 (2013).
Yuzvinsky, T. D., Fennimore, A. M., Mickelson, W., Esquivias, C. & Zettl, A. Precision cutting of nanotubes with a low-energy electron beam. Appl. Phys. Lett. 86, 053109 (2005).
Levita, G., Restuccia, P. & Righi, M. C. Graphene and MoS2 interacting with water: a comparison by ab initio calculations. Carbon 107, 878–884 (2016).
Hueso, J. L., Espinosa, J. P., Caballeroa, A., Cotrino, J. & Gonzalez-Elipe, A. R. XPS investigation of the reaction of carbonwith NO, O2, N2 and H2O plasmas. Carbon 45, 89–96 (2007).
Grazia, G. et al. Water at charged interfaces. Nat. Rev. Chem. 5, 466–485 (2021).
Gopinadhan, K. et al. Complete steric exclusion of ions and proton transport through confined monolayer water. Science 363, 145–148 (2019).
Siria, A. et al. Giant osmotic energy conversion measured in a single transmembrane boron nitride nanotube. Nature 494, 455–458 (2013).
Bocquet, L. & Charlaix, E. Nanofluidics, from bulk to interfaces. Chem. Soc. Rev. 39, 1073–1095 (2010).
Grosjean, B., Bocquet, M. L. & Vuilleumier, R. Versatile electrification of two-dimensional nanomaterials in water. Nat. Commun. 10, 1656 (2019).
Secchi, E., Niguès, A., Jubin, L., Siria, A. & Bocquet, L. Scaling behavior for ionic transport and its fluctuations in individual carbon nanotubes. Phys. Rev. Lett. 116, 154501 (2016).
Mouterde, T. & Bocquet, L. Interfacial transport with mobile surface charges and consequences for ionic transport in carbon nanotubes. Eur. Phys. J. E 41, 148 (2018).
Maduar, S. R., Belyaev, A. V., Lobaskin, V. & Vinogradova, O. I. Electrohydrodynamics near hydrophobic surfaces. Phys. Rev. Lett. 114, 118301 (2015).
Manghi, M., Palmeri, J., Yazda, K., Henn, F. & Jourdain, V. Role of charge regulation and flow slip on the ionic conductance of nanopores: an analytical approach. Phys. Rev. E 98, 012605 (2018).
Biesheuvel, P. M. & Bazant, M. Z. Analysis of ionic conductance of carbon nanotubes. Phys. Rev. E 94, 050601 (2016).
Uematsu, Y., Netz, R. R., Bocquet, L. & Bonthuis, D. J. Crossover of the power-law exponent for carbon nanotube conductivity as a function of salinity. J. Phys. Chem. B 122, 2992–2997 (2018).
Joly, L., Ybert, C., Trizac, E. & Bocquet, L. Liquid friction on charged surfaces: from hydrodynamic slippage to electrokinetics. J. Chem. Phys. 125, 204716 (2006).
Xie, Y., Fu, L., Niehaus, T. & Joly, L. Liquid-solid slip on charged walls: the dramatic impact of charge distribution. Phys. Rev. Lett. 125, 014501 (2020).
Squires, T. M. Electrokinetic flows over inhomogeneously slipping surfaces. Phys. Fluids 20, 092105 (2008).
Jiandong, F. et al. Single-layer MoS2 nanopores as nanopower generators. Nature 536, 197–200 (2016).
Lin, C.-Y., Combs, C., Su, Y.-S., Yeh, L.-H. & Siwy, S. Rectification of concentration polarization in mesopores leads to high conductance ionic diodes and high performance osmotic power. J. Am. Chem. Soc. 141, 3691–3698 (2019).
Ma, T., Balanzat, E., Janot, J.-M. & Blame, S. Nanopore functionalized by highly charged hydrogels for osmotic energy harvesting. ACS Appl. Mater. Interfaces 11, 12578–12585 (2019).
Gao, M., Tsai, P.-C., Su, Y.-S., Peng, P.-H. & Yeh, L.-H. Single mesopores with high surface charges as ultrahigh performance osmotic power generators. Small 16, 2006013 (2020).
Xiao, F. et al. A general strategy to simulate osmotic energy conversion in multi-pore nanofluidic systems. Mater. Chem. Front. 2, 935–941 (2018).
Gao, J. et al. Understanding the giant gap between single-pore- and membrane-based nanofluidic osmotic power generators. Small 215, 1804279 (2019).
Fumagalli, L. et al. Anomalously low dielectric constant of confined water. Science 360, 1339–1342 (2018).
L.B. thanks R. Netz and B. Rotenberg for fruitful discussions. We thank the Institut des Matériaux de Paris Centre (IMPC FR2482) for servicing the XPS instrumentation, as well as A. Walton for his help with XPS measurements and valuable discussions. L.B. acknowledges funding from the EU H2020 Framework Programme/ERC Advanced Grant agreement number 785911-Shadoks and ANR project Neptune. A.S. acknowledges funding from the EU H2020 Framework Programme/ERC Starting Grant agreement number 637748-NanoSOFT. L.B. and A.S. acknowledge support from the Horizon 2020 programme through Grant number 899528-FET-OPEN-ITS-THIN. K.S.V. acknowledges the Marie Curie Individual Fellowship from the EU H2020 Framework Programme, through grant number 836434, GraFludicDevices. A.K. acknowledges the Ramsay Memorial Fellowship and also funding from the Royal Society research grant RGS/R2/202036. B.R. acknowledges the Royal Society fellowship and funding from the EU H2020 Framework Programme/ERC Starting Grant number 852674 AngstroCAP. This work has received the support of the Institut Pierre-Gilles de Gennes (programme ANR-10-IDEX-0001-02 PSL and ANR-10-LABX-31).
The authors declare no competing interests.
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Emmerich, T., Vasu, K.S., Niguès, A. et al. Enhanced nanofluidic transport in activated carbon nanoconduits. Nat. Mater. 21, 696–702 (2022). https://doi.org/10.1038/s41563-022-01229-x