Ultrahigh Proton Conduction in Two Highly Stable Ferrocenyl Carboxylate Frameworks

Abstract

Nowadays, although research of proton conductive materials has been extended from traditional sulfonated polymers to novel crystalline solid materials such as MOFs, COFs, and HOFs, research on crystalline ferrocene-based carboxylate materials is very limited. Herein, we selected two hydrogen-bonded and π–π interactions-supported ferrocenyl carboxylate frameworks (FCFs), [FcCO­(CH2)2COOH] (FCF 1) and [FcCOOH] (FCF 2) (Fc = (η5-C5H5)­Fe­(η5-C5H4)) to fully investigate their water-mediated proton conduction. Their excellent thermal, water, and chemical stabilities were confirmed by the means of thermogravimetric analyses, PXRD, and SEM determinations. The two FCFs indicate temperature- and humidity-dependent proton conductive features. Intriguingly, their ultrahigh proton conductivities are 1.17 × 10–1 and 1.01 × 10–2 S/cm, respectively, under 100 °C and 98% RH, which not only are comparable to the commercial Nafion membranes but also rank among the highest performing MOFs, HOFs, and COFs ever described. On the basis of the structural analysis, calculated E a value, H2O vapor adsorption, PXRD, and SEM measurements, reasonable conduction mechanisms are highlighted. Our research provides a novel inspiration for finding new high proton conducting crystalline solid materials. Importantly, the outstanding conducting performance of 1 and 2 suggests their, hopefully, potential in fuel cells and related electrochemical fields.

Two Highly Stable Proton Conductive Cobalt(II)–Organic Frameworks as Impedance Sensors for Formic Acid

“…In the impedance diagram, at high frequency there is as emicircle and the low frequency gives as pur.I ns ome Nyquist plots, there are two clearly depressed semicircles at high or low frequencies, which correspond to the bulk phase and grain boundary,r espectively. [51,52] The linear part of the Nyquist diagram shows the ion barrier effect on the electrodes and eliminates the probability of electron transfer. [36] The equivalent circuit of 1 (2)L R(C(QR)) (LR(Q(R(QR)))) were fitted with the Nyquist plot by using the ZSimpWin program.…”

Electrochemical Applications of Ferrocene‐Based Coordination Polymers

“…[29] Fc-CPs are widely used as functional materials with interesting magnetic, optical, and redox properties. [29][30][31][32][33] Fc itself offers synthetic route diversity, interesting redox behavior, [34][35][36] and can be easily functionalized by substitution at cyclopentadienyl rings. [35] Thus, the properties of the modified complex can be precisely controlled to allow diverse applications.…”

“…Since its discovery in 1951, Fc and its derivatives have been extensively studied [29] . Fc‐CPs are widely used as functional materials with interesting magnetic, optical, and redox properties [29–33] . Fc itself offers synthetic route diversity, interesting redox behavior, [34–36] and can be easily functionalized by substitution at cyclopentadienyl rings [35] .…”

Triazole‐Modified Molybdenum Oxide with High Proton Conductivity

“…Proton-exchange membrane fuel cells (PEMFCs) as a clean energy resource have aroused extensive attention due to their efficient energy conversion with water as the only byproduct during reaction process. [1][2][3][4] Proton-exchange membrane (PEM) is the core component of PEMFCs. [5] Nafion, a type of perfluorosulfonated copolymer [6] containing terminal sulfonic acid groups, is the commercial PEM, which has high proton conductivity under high humidity conditions.…”

“…Proton‐exchange membrane fuel cells (PEMFCs) as a clean energy resource have aroused extensive attention due to their efficient energy conversion with water as the only byproduct during reaction process . Proton‐exchange membrane (PEM) is the core component of PEMFCs .…”