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2024 | Book

Novel Proton Conducting in Free-Standing Coordination Polymer Membranes

Author: Jiangfeng Lu

Publisher: Springer Nature Singapore

Book Series : Springer Theses

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About this book

This book investigates the development of high proton conduction properties free-standing two-dimensional coordination polymer membranes, with the goal of elucidating the mechanical flexibility, proton conduction behavior, and structural characteristics of these materials under varying environmental conditions. The book evaluates the possible uses of these membranes in flexible electronics and energy technologies and thoroughly examines proton conduction mechanisms using an interdisciplinary research approach that combines chemistry, physics, materials science, and engineering. The most recent scientific developments in novel proton conduction materials are covered, along with preparation and structural characterization procedures and their possible uses in energy, environmental, and electronic technology applications. The research findings presented are extremely important for advancing the creation of clean energy technologies and tackling the problem of climate change. They are also especially relevant given the rising demand for sustainable energy technologies throughout the world.

Table of Contents

Frontmatter
Chapter 1. General Introduction
Abstract
This section delves into the groundbreaking discovery of proton conduction in free-standing coordination polymer membranes (PCPs). These PCPs are crafted through the intricate self-assembly process of metal ions with organic linkers, resulting in exceptional crystallinity and adjustable porosity. The study zeroes in on the pivotal Grotthuss and Vehicle mechanisms for proton transfer, meticulously evaluating their conductivity using AC impedance spectroscopy and single-crystal analysis. The innovation is underscored by the development of supple yet robust PCP membranes, designed to uphold their performance even under mechanical strain, thereby highlighting their immense potential for application in the next wave of protonic devices.
Jiangfeng Lu
Chapter 2. High-Performance All-Solid-State Proton Rectifier Using a Heterogeneous Membrane Composed of Coordination Polymer and Layered Double Hydroxide
Abstract
Rational control of unidirectional proton transport is highly challenging, primarily owing to the difficulty in introducing an asymmetric factor into proton-conducting media. In this study, free-standing membranes of a proton-conducting two-dimensional porous coordination polymer, Cu2(CuTCPP) (H2TCPP: 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) and a hydroxide ion-conducting layered double hydroxide, Mg–Al–LDH(NO3), were combined to generate a pH gradient in the conducting media. The current–voltage measurements revealed that the heterogeneous membrane exhibits a significant unidirectional proton transport with a proton rectification ratio exceeding 200 under 90% relative humidity in the initial voltage scan. This value is the highest among the reported all-solid-state proton rectifiers. The high designability of both components with well-defined structures, which is in contrast to the organic polymers used so far, provides a new avenue for developing and understanding the proton-rectifying behavior in the solid state.
Jiangfeng Lu
Chapter 3. Robust Proton Conduction Against Mechanical Stress in Flexible Free-Standing Membrane Composed of Two-Dimensional Coordination Polymer
Abstract
Introduction of mechanical flexibility into proton-conducting coordination polymers (CPs) is in high demand for future protonic applications such as fuel cells and hydrogen sensors. Whereas such mechanical properties have been primarily investigated in one-dimensional (1D) CPs, in this study we successfully fabricated highly flexible free-standing-type CP membranes with a high surface-to-volume ratio, which is beneficial for the increased performance in the foregoing applications. We employed a layered CP, Cu2(NiTCPP) (H4(H2TCPP); 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin), in which a two-dimensional (2D) square grid sheet composed of tetradentate nickel porphyrins and paddlewheel-type copper dimers is connected to each other by weak van der Waals forces. Mechanical flexibility was evaluated by bending and tensile tests; flexural and Young’s moduli of the membrane are significantly higher than that of conventional Nafion membranes. Electrochemical impedance spectroscopy revealed that the in-plane proton conductivity of the membrane was almost kept even by applying bending stress. Because the X-ray diffraction analysis indicates that proton-conducting pathway through the hydrogen-bonding network is kept intact during the bending operation, our present study provides a promising strategy for fabricating new and more advanced 2D CPs without using any substrates and addition polymers for protonic devices.
Jiangfeng Lu
Chapter 4. Proton-Conducting Behavior in Flexible Coordination Polymer Free-Standing Membranes
Abstract
Applying CP to flexible devices remains a considerable challenge because of its brittleness. CP structure of low dimension usually plays a crucial role in deciding on the mechanical flexibility, typical dimensional coordination chain that acts as a rigid frame and the other two directions through many weak molecular interactions. We employed a series layered CP, Cu2(MTCPP) (H4(H2TCPP); 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) (M = Ni(II), Cu(II), Zn(II)), in which a two-dimensional (2D) square grid sheet composed of tetradentate metal porphyrins and paddlewheel-type copper dimers is connected by weak van der Waals forces. These membranes composed with two-dimensional (2D) nanosheets show good orientation and bending tests evaluated their mechanical flexibility. Electrochemical impedance spectroscopy revealed that the in-plane proton conductivities of the membranes show different conductivities due to the difference in the hydration coordination ability of central porphyrin metals. Our present study provides a promising strategy for fabricating new and more advanced 2D CPs without using substrates and additional polymers for photonic devices.
Jiangfeng Lu
Chapter 5. General Conclusion
Abstract
This Ph.D. thesis presents the fabrication of flexible, free-standing 2D coordination polymer membranes with specific proton-conducting properties. The study explores the principles of proton conduction, fabricates CP membranes, and demonstrates robust proton conduction under mechanical stress. A record rectification ratio was achieved with a heterogeneous membrane, and the membranes show excellent bending stability, indicating potential for flexible protonic devices without a polymer matrix.
Jiangfeng Lu
Backmatter
Metadata
Title
Novel Proton Conducting in Free-Standing Coordination Polymer Membranes
Author
Jiangfeng Lu
Copyright Year
2024
Publisher
Springer Nature Singapore
Electronic ISBN
978-981-9779-13-0
Print ISBN
978-981-9779-12-3
DOI
https://doi.org/10.1007/978-981-97-7913-0

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