Issue 45, 2019

A fully reduced {V IV18O42} host and VO43−, Cl as guest anions: synthesis, characterization and proton conductivity

Abstract

Fully reduced polyoxometalates (POMs) generally have a high negative charge that can be compensated by diverse cations including protons. The POMs with a large number of acidic protons often exhibit solid state proton conduction. We synthesized two polyoxovanadate (POV)-based compounds, [Na7(H2O)14][H8VIV18O42(VVO4)]·N2H4·7H2O (1) and [Na5(H2O)16][H8VIV18O42(Cl)]·4N2H4·6H2O (2), each of which accommodates eight acidic protons (per formula unit) acting as the cations. Compounds 1 and 2 have been characterized by routine analytical techniques, such as, IR, Raman, XPS, PXRD, TGA, etc., elemental analysis, and unambiguously by single crystal X-ray diffraction. As expected, compounds 1 and 2 having eight protons per formula unit exhibit proton conductivity in the solid state. Proton conductivity measurements of compounds 1 and 2 were performed (a) at variable temperature (20–50 °C) at constant humidity (70% RH) and (b) variable humidity (relative humidity from 40% to 70%) at constant temperature (30 °C). The proton conductivity was observed to increase with an increase in temperature and humidity. The best conductivity values were obtained at 50 °C at a RH of 70% and found to be 3.62 × 10−3 S cm−1 for compound 1 and 2.16 × 10−4 S cm−1 for compound 2. Reproducibility of proton conductivity was verified by repetitive data recording over a long time period and determining the mean value of conductivity of compounds 1 and 2 at 50 °C. The activation energies for 1 (23.34 kJ mol−1) and 2 (18.40 kJ mol−1) calculated from Arrhenius plots of temperature dependence of proton conductivity suggest a Grotthuss proton hopping mechanism for solid state proton conduction. Controlled experiments have shown that the synthesized compounds 1 and 2 are stable and robust under operational conditions.

Graphical abstract: A fully reduced {VIV18O42} host and VO43−, Cl− as guest anions: synthesis, characterization and proton conductivity

Supplementary files

Article information

Article type
Paper
Submitted
14 এপ্রিল 2019
Accepted
19 জুন 2019
First published
20 জুন 2019

New J. Chem., 2019,43, 17670-17679

A fully reduced {VIV18O42} host and VO43−, Cl as guest anions: synthesis, characterization and proton conductivity

S. Mulkapuri, S. K. Kurapati, S. Mukhopadhyay and S. K. Das, New J. Chem., 2019, 43, 17670 DOI: 10.1039/C9NJ01918A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements