Volume 62, Issue 29 e202302376
Research Article

Superprotonic Conductivity of MOFs Confining Zwitterionic Sulfamic Acid as Proton Source and Conducting Medium

Dr. Amitosh Sharma

Dr. Amitosh Sharma

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

These authors contributed equally to this work.

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Dr. Jaewoong Lim

Dr. Jaewoong Lim

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

These authors contributed equally to this work.

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Seonghwan Lee

Seonghwan Lee

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

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Dr. Seungwan Han

Dr. Seungwan Han

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

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Dr. Junmo Seong

Dr. Junmo Seong

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

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Prof. Dr. Seung Bin Baek

Prof. Dr. Seung Bin Baek

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

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Prof. Dr. Myoung Soo Lah

Corresponding Author

Prof. Dr. Myoung Soo Lah

Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea

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First published: 09 May 2023
Citations: 8

Graphical Abstract

Strategic loading of dual-functioning zwitterionic sulfamic acid in MOFs leads to proton conductivity of the order of 10−1 S cm−1. This high conductivity is the result of higher loading of sulfamic acid, which can act as both a proton source due to its acidity and a conducting medium due to its extensive hydrogen-bonding ability and zwitterion effect.

Abstract

A few metal–organic frameworks (MOFs), which typically use strong acids as proton sources, display superprotonic conductivity (≈10−1 S cm−1); however, they are rare due to the instability of MOFs in highly acidic conditions. For the first time, we report superprotonic conductivity using a moderately acidic guest, zwitterionic sulfamic acid (HSA), which is encapsulated in MOF-808 and MIL-101. HSA acts not only as a proton source but also as a proton-conducting medium due to its extensive hydrogen bonding ability and zwitterion effect. A new sustained concentration gradient method results in higher HSA encapsulation compared to conventional methods, producing 10HSA@MOF-808-(bSA)2 and 8HSA@MIL-101. These MOFs show impressive superprotonic conductivity of 2.47×10−1 and 3.06×10−1 S cm−1, respectively, at 85 °C and 98 % relative humidity, and maintain stability for 7 days.

Conflict of interest

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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