am9b01121_si_001.pdf (3.23 MB)
Designing UiO-66-Based Superprotonic Conductor with the Highest Metal–Organic Framework Based Proton Conductivity
journal contribution
posted on 2019-03-19, 00:00 authored by Subhabrata Mukhopadhyay, Joyashish Debgupta, Chandani Singh, Rudraditya Sarkar, Olivia Basu, Samar K. DasMetal–organic framework (MOF)
based proton conductors have
received immense importance recently. The present study endeavors
to design two post synthetically modified UiO-66-based MOFs and examines
the effects of their structural differences on their proton conductivity.
UiO-66-NH2 is modified by reaction with sultones to prepare
two homologous compounds, that is, PSM 1 and PSM
2, with SO3H functionalization in comparable extent
(Zr:S = 2:1) in both. However, the pendant alkyl chain holding the
−SO3H group is of different length. PSM 2 has longer alkyl chain attachment than PSM 1. This
difference in the length of side arms results in a huge difference
in proton conductivity of the two compounds. PSM 1 is
observed to have the highest MOF-based proton conductivity (1.64 ×
10–1 S cm–1) at 80 °C, which
is comparable to commercially available Nafion, while PSM 2 shows significantly lower conductivity (4.6 × 10–3 S cm–1). Again, the activation energy for proton
conduction is one of the lowest among all MOF-based proton conductors
in the case of PSM 1, while PSM 2 requires
larger activation energy (almost 3 times). This profound effect of
variation of the chain length of the side arm by one carbon atom in
the case of PSM 1 and PSM 2 was rather surprising
and never documented before. This effect of the length of the side
arm can be very useful to understand the proton conduction mechanism
of MOF-based compounds and also to design better proton conductors.
Besides, PSM 1 showed proton conductivity as high as
1.64 × 10–1 S cm–1 at 80
°C, which is the highest reported value to date among all MOF-based
systems. The lability of the −SO3H proton of the
post synthetically modified UiO-66 MOFs has theoretically been determined
by molecular electrostatic potential analysis and theoretical pKa calculation of models of functional sites
along with relevant NBO analyses.
History
Usage metrics
Categories
Keywords
3 H protonUiO -66-based MOFsalkyl chain attachmentproton conduction mechanismMOF-based proton conductors3 H functionalizationside arm3 H grouplengthpendant alkyl chainUiO -66 MOFsproton conductorsNBOPSM 1PSM 2Designing UiO -66-Based Superprotonic Conductorproton conductivityside arms resultsUiO -66-NH 2post syntheticallyactivation energy
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC