Proton-Coupled Reversible Redox Reaction of Zinc-Terephthalate Metal-Organic Framework. (13th December 2018)

• Record Type: Journal Article
• Authors: Hirai, Yuji; Ueda, Shotaro; Nishiumi, Nobuyuki; Sun, He; Matsushima, Yuta; Masuhara, Akito; Shiroishi, Hidenobu; Yoshida, Tsukasa
• Is Part Of: ECS transactions. Volume 88:Number 1(2018)
• Page Start: 259
• Page End: 268
• Publication Date: 2018-12-13
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/08801.0259ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

Abstract : Redox properties of metal-organic frameworks (MOFs) between Zn 2+ ion and terephthalic acid (TPA) in compositions as Zn3 (OH)4 (TPA)・6H2 O, Zn4 (OH)6 (TPA) and Zn2 (OH)2 (TPA)・H2 O were examined. Among them, Zn4 (OH)6 (TPA) exhibited a remarkable reversible redox centered at around -1 V vs. Ag/AgCl in a neutral KCl aqueous solution. While cathodic reduction was slow resulting in a broad peak in its cyclic voltammogram, the oxidation was relatively fast, both showing diffusion-limited behavior. Slight acidification of the electrolyte resulted in a significant acceleration of the redox, while the redox potential was independent on pH. Peak splitting systematically increased on increasing the scan rate. Thus, proton exchange by TPA was concluded, for its field driven migration to limit the reaction rates. Potentiostatic charging / discharging experiments confirmed coulombic reversibility over 92% and revealed an active fraction of 17.7% per coated molar amount, so that the proton-coupled redox was achieved within the MOF bulk.