Comparative Studies on the Proton Conductivities of Hafnium-Based Metal–Organic Frameworks and Related Chitosan or Nafion Composite Membranes

Abstract

Hafnium (Hf)-based UiO-66 series metal−organic frameworks (MOFs) have been widely studied on gas storage, gas separation, reduction reaction, and other aspects since they were first prepared in 2012, but there are few studies on proton conductivity. In this work, one Hf-based MOF, Hf-UiO-66-fum showing UiO-66 structure, also known as MOF-801-Hf, was synthesized at room temperature using cheap fumaric acid as the bridging ligand, and then imidazole units were successfully introduced into MOF-801-Hf to obatin a doped product,

Two Dual-Function Zr/Hf-MOFs as High-Performance Proton Conductors and Amines Impedance Sensors

“…As listed in Table , under similar testing conditions, although the best σ values of the two compounds are slightly lower than those of several recently reported Zr/Hf-based MOFs, ,− which can be compared to previous MOFs and much higher than some other MOFs. ,,,− Note that the two compounds with outstanding water and chemical stabilities, and high σ values could be used as proton-conductive and sensing materials …”

Comparative study on proton conductivity of a polypyridinyl multicarboxylate-based hydrogen-bonded organic framework and related chitosan composite membrane

“…The proton conductivity of the pure CS membrane increased from 5.38 × 10 −3 to 1.25 × 10 −2 S cm −1 at 98% RH as the temperature increased from 70 to 100 °C, which is not much different from the literature reports. 46,47 The results show that with the increase of HOF 1 doping from 2% to 4%, σ increases from 2.20 × 10 −2 to 2.61 × 10 −2 S cm −1 . However, with augmentation of the doping amount, σ did not increase, but instead decreased to 1.23 × 10 −2 S cm −1 (8% loading) (Fig.…”

Correlation of Structures with Proton Conductivity of 1D Coordination Polymers: Higher Proton Conductivity Due to Synergy of Encapsulated Sulfate Ions and Water Molecules

“…The activation energy required for proton conduction by the material was calculated from the variable-temperature conductivity data obtained at 98% RH. The linearly fitted data in the Arrhenius equation ln­(σ T ) = ln A – E a / k B T ( E a activation energy, A pre-exponential factor, T temperature, k B Boltzmann constant, and σproton conductivity) in the temperature range 30–90 °C give an estimated activation energy of 0.26 and 0.37 eV for CP-1 and CP-2 , respectively; both the values lie below the range of E a < 0.4 eV, suggesting that the proton conduction occurs through the Grotthuss mechanism (Figure c); however, the higher activation energy in CP-2 and the slight deviation of Arrhenius plot from linearity at the higher temperature also indicate that vehicular mechanism may coexist in this proton conduction under such humidity-assisted proton conductivity measurement conditions. − Further, the durability of the material was confirmed from the well-matched PXRD patterns (Figures S6 and S7) of CPs and the preserved morphologies from the SEM images (Figure ) after electrochemical experiments.…”