TY - JOUR
T1 - Negative dielectric constant of water confined in nanosheets
AU - Sugahara, Akira
AU - Ando, Yasunobu
AU - Kajiyama, Satoshi
AU - Yazawa, Koji
AU - Gotoh, Kazuma
AU - Otani, Minoru
AU - Okubo, Masashi
AU - Yamada, Atsuo
N1 - Funding Information:
This work was financially supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan under the “Elemental Strategy Initiative for Catalysts and Batteries (ESICB).” This work was also supported by MEXT, Japan, and Grant-in-Aid for Specially Promoted Research Number 15H05701. M. Okubo was financially supported by JSPS KEKENHI Grant Numbers JP15H03873, JP16H00901, and 18H03924. We are grateful to Satomichi Nishihara for implementation of the 3D-RISM into Quantum Espresso package. X-ray absorption spectroscopy was conducted under the approval of the Photon Factory Program Advisory Committee (Proposal 2016G031 and 2018G082).
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Electric double-layer capacitors are efficient energy storage devices that have the potential to account for uneven power demand in sustainable energy systems. Earlier attempts to improve an unsatisfactory capacitance of electric double-layer capacitors have focused on meso- or nanostructuring to increase the accessible surface area and minimize the distance between the adsorbed ions and the electrode. However, the dielectric constant of the electrolyte solvent embedded between adsorbed ions and the electrode surface, which also governs the capacitance, has not been previously exploited to manipulate the capacitance. Here we show that the capacitance of electric double-layer capacitor electrodes can be enlarged when the water molecules are strongly confined into the two-dimensional slits of titanium carbide MXene nanosheets. Using electrochemical methods and theoretical modeling, we find that dipolar polarization of strongly confined water resonantly overscreens an external electric field and enhances capacitance with a characteristically negative dielectric constant of a water molecule.
AB - Electric double-layer capacitors are efficient energy storage devices that have the potential to account for uneven power demand in sustainable energy systems. Earlier attempts to improve an unsatisfactory capacitance of electric double-layer capacitors have focused on meso- or nanostructuring to increase the accessible surface area and minimize the distance between the adsorbed ions and the electrode. However, the dielectric constant of the electrolyte solvent embedded between adsorbed ions and the electrode surface, which also governs the capacitance, has not been previously exploited to manipulate the capacitance. Here we show that the capacitance of electric double-layer capacitor electrodes can be enlarged when the water molecules are strongly confined into the two-dimensional slits of titanium carbide MXene nanosheets. Using electrochemical methods and theoretical modeling, we find that dipolar polarization of strongly confined water resonantly overscreens an external electric field and enhances capacitance with a characteristically negative dielectric constant of a water molecule.
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U2 - 10.1038/s41467-019-08789-8
DO - 10.1038/s41467-019-08789-8
M3 - Article
C2 - 30787445
AN - SCOPUS:85061793071
SN - 2041-1723
VL - 10
JO - Nature communications
JF - Nature communications
IS - 1
M1 - 850
ER -