Electrochemistry of Porous Materials

Antonio Doménech Carbó

• Publisher: CRC Press
• Year: 2021
• Print ISBN:
  9781032474267
• eBook ISBN:
  9781000370478
• Topic: Physical Sciences
• Subtopic: Chemistry
• Index: Chemistry

Electrochemistry of Porous Materials describes essential theoretical aspects of the electrochemistry of nanostructured materials and primary applications, incorporating the advances in the field in the last ten years including recent theoretical formulations and the incorporation of novel materials.

Concentrating on nanostructured micro- and mesoporous materials, the highly anticipated Second Edition offers a more focused and practical analysis of key porous materials considered relatively homogeneous from an electrochemical point of view. The author details the use of electrochemical methods in materials science for characterization and their applications in the fields of analysis, energy production and storage, environmental remediation, and the biomedical arena.

Additional features include:

• Incorporates new theoretical advances in the voltammetry of porous materials and multiphase porous electrochemistry.
• Includes new developments in sensing, energy production and storage, degradation of pollutants, desalination and drug release.
• Describes redox processes for different porous materials, assessing their electrochemical applications.
• Written at an accessible and understandable level for researchers and graduate students working in the field of material chemistry.

Selective and streamlined, Electrochemistry of Porous Materials, Second Edition culls a wide range of relevant and practically useful material from the extensive literature on the subject, making it an invaluable reference for readers of all levels of understanding.

1	Porous Materials and Electrochemistry

1.1 Porous Materials, Concept, and Classifications

Porous materials have attracted considerable attention in the last decades because of their wide variety of scientific and technological applications. In its most generalized meaning, the term pore designs a limited space or cavity in a (at least apparently) continuous material. Porous materials comprise inorganic compounds, such as aluminosilicates, and biological membranes and tissues. According to the International Union of Pure and Applied Chemistry (IUPAC), pores are classified into three categories: micropores (size less than 2 nm), mesopores (size between 2 and 50 nm), and macropores (size larger than 50 nm) [1].

Porous materials discussed at the International Conference on Materials for Advanced Technologies in 2005 included clay minerals, silicates, aluminosilicates, organosilicon, metals, silicon, metal oxides, carbons and carbon nanotubes, polymers and coordination polymers or metal-organic frameworks (MOFs), metal and metal oxide nanoparticles, thin films, membranes, and monoliths [2].

Fundamental and applied research dealing with novel porous materials is addressed to improve template-synthesis strategies, chemical modification of porous materials via molecular chemistry, construction of nanostructures of metals and metal oxides with controlled interior nanospace, and reticular design of MOFs with pore sizes ranging from the micropore to the mesopore scales, among others. Porous materials are useful for sensing, catalysis, shape- and size-selective absorption and adsorption of reagents, gas storage, electrode materials, etc.

Because of the considerable variety of materials to be categorized as porous, several classifications can be proposed. Thus, based on the distribution of pores within the material, we can distinguish between regular and irregular porous materials; according to the size distribution of pores, one can separate between uniformly-sized and non-uniformly-sized porous materials.

From a structural point of view, porous materials can be the result of building blocks following an order of construction that can be extended from centimeter to the nanometer levels. Porous materials can range from highly ordered crystalline materials, such as aluminosilicates or metal-organic frameworks, to amorphous sol-gel compounds, polymers, and fibers. This text will focus on materials that have porous structures; ion-insertion solids that have no micro- or mesoporous structures will not be treated here. To present a systematic approach from the ‘electrochemical’ point of view, porous materials will be divided here into:

• Porous metals;

• Porous silicates and aluminosilicates;

• Porous metal oxides and related compounds (including pillared oxides, laminar hydroxides, and polyoxometalates);

• Porous sulfides, nitrides, and phosphides;

• Metal-organic frameworks (MOFs);

• Porous carbons, nanotubes (CNTs), graphene and its derivatives, and fullerenes; and

• Porous organic polymers and hybrid materials.

This list—although not exhaustive of the entire range of porous materials—attempts to cover those that can be described in terms of extended porous structures and whose electrochemistry has been extensively studied. In the last years, additionally, there has been growing interest in the preparation of nanostructures of metal and metal oxides with controlled interior nanospace, while a variety of nanoscopic porogen such as dendrimers, cross-linked and core-corona nanoparticles, hybrid copolymers, and cage supramolecules are currently under intensive research [3]. Several of such nanostructured systems will be treated along with the text, although the study in extenso of their electrochemistry should be treated elsewhere.

The most relevant characteristic of porous materials is the disposal of a high effective surface/volume relationship, usually expressed in terms of their specific surface area (area per mass unit) that can be determined from nitrogen adsorption/desorption data. Different methods are available to determine the specific surface area (BET, Langmuir, and Kaganer), micropore volume (t-plot, α_s, and Dubinin-Astakhov), and mesopore diameter (Barrett-Joyner-Halenda). Table 1.1 summarizes the values of specific surface area reported for selected porous materials. A functional classification of porous materials (see Figure 1.1) can be made based on their degree of long-range order (influencing molecular sieving capacity) and their intermolecular bond strengths (influencing thermal and/or chemical stability) [4].

Table 1.1
Typical Values for the Specific Surface Area of Selected Porous Materials

Material	Specific surface area (m^2 g ^–1)
Zeolite X	700
SBA-15	650
MCM-41	850
Activated carbon	2,000
Nanocubes MOF-5	3,500

Figure 1.1 A Model of Functional Classification of Porous Solids.

1.2 Mixed Porous Materials

Porous material chemistry involves a variety of systems, which will generically be termed here as mixed systems, from the combination of different structural moieties resulting in significant modifications of the properties of the pristine porous materials. In this group, we can include quite varied materials:

• Composites constructed by the addition of a binder to porous materials and, eventually, other components, forming mixtures for definite applications. This kind of system is frequently used to prepare composite electrodes.

• Functionalized materials prepared by attachment of functional groups to a porous matrix.

• Materials with encapsulated species where molecular guests are entrapped into cavities of the porous host material.

• Doped materials where a structural component of the material becomes partially substituted by a dopant species, or when external species ingress in the original material as an interstitial ion. The term doping is applied to yttria-doped zirconia used for potentiometric determination of O₂, but also to describe the incorporation of Li⁺ in polymers and nanostructured carbons.

• Intercalation materials where different nanostructured components are attached to the porous matrix. This is the case with metal and metal oxide nanoparticles generated into zeolites and mesoporous silicates, or organic polymers intercalated between laminar hydroxides.

From several applications, it is convenient to describe much of the above systems as resulting from the modification of the parent porous materials by a second component. In this sense, one can separate network modification, network building, and network functionalization processes. Network modification exists when the final structure of the parent material is modified because of its combi...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Contents
• Foreword
• Preface
• Contributors
• List of Abbreviations
• Chapter 1 Porous Materials and Electrochemistry
• Chapter 2 Electrochemical Processes at Porous Electrodes
• Chapter 3 Electrochemical Processes at Ion-Permeable Solids
• Chapter 4 Electrocatalysis
• Chapter 5 Electrochemistry of Aluminosilicates
• Chapter 6 Electrochemistry of Metal-Organic Frameworks
• Chapter 7 Electrochemistry of Porous Metals and Anodic Metal Oxide Films
• Chapter 8 Electrochemistry of Porous Oxides and Related Materials
• Chapter 9 Sulfides, Nitrides, Phosphides
• Chapter 10 Electrochemistry of Porous Carbon-Based Materials
• Chapter 11 Electrochemistry of Porous Polymers and Hybrid Materials
• Chapter 12 Electrochemical Sensing via Porous Materials
• Chapter 13 Electrochemical Gas Sensing
• Chapter 14 Supercapacitors, Batteries, Fuel Cells, and Related Applications
• Chapter 15 Magnetoelectrochemistry and Photoelectrochemistry of Porous Materials
• Chapter 16 Microporous Materials in Electrosynthesis, Environmental Remediation, and Drug Release
• Additional Literature
• Index