Proton Hopping and Long-Range Transport in the Protic Ionic Liquid [Im][TFSI], Probed by Pulsed-Field Gradient NMR and Quasi-Elastic Neutron Scattering

被引：52

作者：

Hoarfrost, Megan L. ^{[1
,2
]}

Tyagi, Madhusudan ^{[3
,4
]}

Segalman, Rachel A. ^{[1
,5
]}

Reimer, Jeffrey A. ^{[1
,2
]}

机构：

[1] Univ Calif Berkeley, Dept Chem & Biomol Engn, Berkeley, CA 94720 USA

[2] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Energy & Environm Technol Div, Berkeley, CA 94720 USA

[3] Natl Inst Stand & Technol, Ctr Neutron Res, Gaithersburg, MD 20899 USA

[4] Univ Maryland, Dept Mat Sci & Engn, College Pk, MD 20742 USA

[5] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Div Mat Sci, Berkeley, CA 94720 USA

来源：

JOURNAL OF PHYSICAL CHEMISTRY B | 2012年 / 116卷 / 28期

基金：

美国国家科学基金会;

关键词：

NUCLEAR-MAGNETIC-RESONANCE; SOLID-STATE; RELAXATION PROCESSES; DIFFUSION; DYNAMICS; IMIDAZOLE; HYDROGEN; MECHANISM; MOBILITY; WATER;

D O I：

10.1021/jp3044237

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The management of proton conductivity in the protic ionic liquid imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) is investigated via the use of quasi-elastic neutron scattering (QENS) and pulsed-field gradient NMR. The introduction of excess neutral imidazole to [Im][TFSI] leads to enhanced conductivity. We find that proton dynamics in [Im][TFSI] with excess imidazole are characterized by proton hopping that is encompassed in the slower of two translational processes, as identified by QENS. This relatively slow process contributes to long-range diffusion more than the faster process. NMR diffusion measurements show that proton hopping decreases with increasing temperature, but significant proton hopping persists even at the maximum experimental temperature of 120 degrees C. This, in combination with minimal ion aggregation, leads to high proton conductivity and a high proton transference number over a wide temperature range.

引用

页码：8201 / 8209

页数：9