Layered 2D Materials and Their Allied Applications
Description
The following topics are discussed in the book's fifteen chapters:
* The research status of the 2D metal-organic frameworks and the different techniques used to synthesize them.
* 2D black phosphorus (BP) and its practical application in various fields.
* Reviews the synthesis methods of MXenes and provides a detailed discussion of their structural characterization and physical, electrochemical and optical properties, as well as applications in catalysis, energy storage, environmental management, biomedicine, and gas sensing.
* The carbon-based materials and their potential applications via the photocatalytic process using visible light irradiation.
* 2D materials like graphene, TMDCs, few-layer phosphorene, MXene in layered form and their heterostructures.
* The structure and applications of 2D perovskites.
* The physical parameters of pristine layered materials, ZnO, transition metal dichalcogenides, and heterostructures of layered materials are discussed.
* The coupling of graphitic carbon nitride with various metal sulfides and oxides to form efficient heterojunction for water purification.
* The structural features, synthetic methods, properties, and different applications and properties of 2D zeolites.
* The methods for synthesizing 2D hollow nanostructures are featured and their structural aspects and potential in medical and non-medical applications.
* The characteristics and structural aspects of 2D layered double hydroxides (LDHs) and the various synthesis methods and role of LDH in non-medical applications as adsorbent, sensor, catalyst, etc.
* The synthesis of graphene-based 2D layered materials synthesized by using top-down and bottom-up approaches where the main emphasis is on the hot-filament thermal chemical vapor deposition (HFTCVD) method.
* The different properties of 2D h-BN and borophene and the various methods being used for the synthesis of 2D h-BN, along with their growth mechanism and transfer techniques.
* The physical properties and current progress of various transition metal dichalcogenides (TMDC) based on photoactive materials for photoelectrochemical (PEC) hydrogen evolution reaction.
* The state-of-the-art of 2D layered materials and associated devices, such as electronic, biosensing, optoelectronic, and energy storage applications.
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Inamuddin, PhD, is an assistant professor at King Abdulaziz University, Jeddah, Saudi Arabia and is also an assistant professor in the Department of Applied Chemistry, Aligarh Muslim University, Aligarh, India. He has extensive research experience in multidisciplinary fields of analytical chemistry, materials chemistry, electrochemistry, renewable energy and environmental science. He has published about 150 research articles in various international scientific journals, 18 book chapters, and 60 edited books with multiple well-known publishers.
Rajender Boddula, PhD, is currently working for the Chinese Academy of Sciences President's International Fellowship Initiative (CAS-PIFI) at the National Center for Nanoscience and Technology (NCNST, Beijing). His academic honors include multiple fellowships and scholarships, and he has published many scientific articles in international peer-reviewed journals, edited books with numerous publishers and has authored twenty book chapters.
Mohd Imran Ahamed received his Ph.D on the topic "Synthesis and characterization of inorganic-organic composite heavy metals selective cation-exchangers and their analytical applications", from Aligarh Muslim University, India in 2019. He has published several research and review articles in SCI journals. His research focusses on ion-exchange chromatography, wastewater treatment and analysis, actuators and electrospinning.
Abdullah M. Asiri is the Head of the Chemistry Department at King Abdulaziz University and the founder and Director of the Center of Excellence for Advanced Materials Research (CEAMR). He is the Editor-in-Chief of the King Abdulaziz University Journal of Science. He has received numerous awards, including the first prize for distinction in science from the Saudi Chemical Society in 2012. He holds multiple patents, has authored ten books and more than one thousand publications in international journals.
Content
Preface xv
1 2D Metal-Organic Frameworks 1
Fengxian Cao, Jian Chen, Qixun Xia and Xinglai Zhang
1.1 Introduction 1
1.2 Synthesis Approaches 2
1.2.1 Selection of Synthetic Raw Materials 3
1.2.2 Solvent Volatility Method 4
1.2.3 Diffusion Method 4
1.2.3.1 Gas Phase Diffusion 4
1.2.3.2 Liquid Phase Diffusion 4
1.2.4 Sol-Gel Method 5
1.2.5 Hydrothermal/Solvothermal Synthesis Method 6
1.2.6 Stripping Method 6
1.2.7 Microwave Synthesis Method 8
1.2.8 Self-Assembly 9
1.2.9 Special Interface Synthesis Method 9
1.2.10 Surfactant-Assisted Synthesis Method 10
1.2.11 Ultrasonic Synthesis 10
1.3 Structures, Properties, and Applications 11
1.3.1 Structure and Properties of MOFs 11
1.3.2 Application in Biomedicine 12
1.3.3 Application in Gas Storage 12
1.3.4 Application in Sensors 13
1.3.5 Application in Chemical Separation 13
1.3.6 Application in Catalysis 14
1.3.7 Application in Gas Adsorption 14
1.4 Summary and Outlook 15
Acknowledgements 16
References 16
2 2D Black Phosphorus 21
Chenguang Duan, Hui Qiao, Zongyut Huang and Xiang Qi
2.1 Introduction 22
2.2 The Research on Black Phosphorus 23
2.2.1 The Structure and Properties 23
2.2.1.1 The Structure of Black Phosphorus 25
2.2.1.2 The Properties of Black Phosphorus 25
2.2.2 Preparation Methods 26
2.2.2.1 Mechanical Exfoliation 28
2.2.2.2 Liquid-Phase Exfoliation 28
2.2.3 Antioxidant 30
2.2.3.1 Degradation Mechanism 30
2.2.3.2 Adding Protective Layer 31
2.2.3.3 Chemical Modification 31
2.2.3.4 Doping 33
2.3 Applications of Black Phosphorus 33
2.3.1 Electronic and Optoelectronic 34
2.3.1.1 Field-Effect Transistors 34
2.3.1.2 Photodetector 35
2.3.2 Energy Storage and Conversion 36
2.3.2.1 Catalysis 36
2.3.2.2 Batteries 37
2.3.2.3 Supercapacitor 38
2.3.3 Biomedical 39
2.4 Conclusion and Outlook 40
Acknowledgements 41
References 41
3 2D Metal Carbides 47
Peiran Hou, Xinxin Fu, Qixun Xia and Zhengpeng Yang
3.1 Introduction 47
3.2 Synthesis Approaches 48
3.2.1 Ti3C2 Synthesis 48
3.2.2 V2C Synthesis 50
3.2.3 Ti2C Synthesis 50
3.2.4 Mo2C Synthesis 51
3.3 Structures, Properties, and Applications 52
3.3.1 Structures and Properties of 2D Metal Carbides 52
3.3.1.1 Structures and Properties of Ti3C2 52
3.3.1.2 Structural Properties of Ti2C 53
3.3.1.3 Structural Properties of Mo2C 53
3.3.1.4 Structural Properties of V2C 54
3.3.2 Carbide Materials in Energy Storage Applications 55
3.3.2.1 Ti3C2 56
3.3.2.2 Ti2C 57
3.3.2.3 V2C 58
3.3.2.4 Mo2C 58
3.3.3 Metal Carbide Materials in Catalysis Applications 60
3.3.3.1 Ti3C2 60
3.3.3.2 V2C 61
3.3.3.3 Mo2C 62
3.3.4 Metal Carbide Materials in Environmental Management Applications 63
3.3.4.1 Ti3C2 in Environmental Management Applications 63
3.3.4.2 Ti2C in Environmental Management Applications 64
3.3.4.3 V2C in Environmental Management Applications 64
3.3.4.4 Mo2C in Environmental Management Applications 65
3.3.5 Carbide Materials in Biomedicine Applications 66
3.3.5.1 Ti3C2 in Biomedicine Applications 66
3.3.5.2 Ti2C in Biomedicine Applications 66
3.3.5.3 V2C in Biomedicine Applications 68
3.3.5.4 Mo2C in Biomedicine Applications 68
3.3.6 Carbide Materials in Gas Sensing Applications 69
3.3.6.1 Ti3C2 in Gas Sensing Applications 69
3.3.6.2 Ti2C in Gas Sensing Applications 69
3.3.6.3 V2C in Gas Sensing Applications 70
3.3.6.4 Mo2C in Gas Sensing Applications 71
3.4 Summary and Outlook 72
Acknowledgements 72
References 73
4 2D Carbon Materials as Photocatalysts 79
Amel Boudjemaa
4.1 Introduction 79
4.2 Carbon Nanostructured-Based Materials 80
4.2.1 Forms of Carbon 80
4.2.2 Synthesis of Carbon Nanostructured-Based Materials 80
4.3 Photo-Degradation of Organic Pollutants 81
4.3.1 Graphene, Graphene Oxide, Graphene Nitride (g-C3N4) 81
4.3.1.1 Graphene-Based Materials 82
4.3.1.2 Graphene Nitride (g-C3N4) 84
4.3.2 Carbon Dots (CDs) 87
4.3.3 Carbon Spheres (CSs) 87
4.4 Carbon-Based Materials for Hydrogen Production 88
4.5 Carbon-Based Materials for CO2 Reduction 90
References 90
5 Sensitivity Analysis of Surface Plasmon Resonance Biosensor Based on Heterostructure of 2D BlueP/MoS2 and MXene 103
Sarika Pal, Narendra Pal, Y.K. Prajapati and J.P. Saini
5.1 Introduction 104
5.2 Proposed SPR Sensor, Design Considerations, and Modeling 107
5.2.1 SPR Sensor and Its Sensing Principle 107
5.2.2 Design Consideration 108
5.2.2.1 Layer 1: Prism for Light Coupling 108
5.2.2.2 Layer 2: Metal Layer 109
5.2.2.3 Layer 3: BlueP/MoS2 Layer 110
5.2.2.4 Layer 4: MXene (Ti3C2Tx) Layer as BRE for Biosensing 110
5.2.2.5 Layer 5: Sensing Medium (RI-1.33-1.335) 110
5.2.3 Proposed Sensor Modeling 110
5.3 Results Discussion 112
5.3.1 Role of Monolayer BlueP/MoS2 and MXene (Ti3C2Tx) and Its Comparison With Conventional SPR 112
5.3.2 Influence of Varying Heterostructure Layers for Proposed Design 114
5.3.3 Effect of Changing Prism Material and Metal on Performance of Proposed Design 115
5.4 Conclusion 125
References 125
6 2D Perovskite Materials and Their Device Applications 131
B. Venkata Shiva Reddy, K. Srinivas, N. Suresh Kumar, S. Ramesh, K. Chandra Babu Naidu, Prasun Banerjee, Ramyakrishna Pothu and Rajender Boddula
6.1 Introduction 131
6.2 Structure 134
6.2.1 Crystal Structure 134
6.2.2 Electronic Structure of 2D Perovskites 134
6.2.3 Structure of Photovoltaic Cell 135
6.3 Discussion and Applications 136
6.4 Conclusion 139
References 139
7 Introduction and Significant Parameters for Layered Materials 141
Umbreen Rasheed, Fayyaz Hussain, Muhammad Imran, R.M. Arif Khalil and Sungjun Kim
7.1 Graphene 143
7.2 Phosphorene 147
7.3 Silicene 148
7.4 ZnO 150
7.5 Transition Metal Dichalcogenides (TMDCs) 151
7.6 Germanene and Stanene 152
7.7 Heterostructures 153
References 156
8 Increment in Photocatalytic Activity of g-C3N4 Coupled Sulphides and Oxides for Environmental Remediation 159
Pankaj Raizada, Abhinadan Kumar and Pardeep Singh
8.1 Introduction 160
8.2 GCN Coupled Metal Sulphide Heterojunctions for Environment Remediation 163
8.2.1 GCN and MoS2-Based Photocatalysts 163
8.2.2 GCN and CdS-Based Heterojunctions 168
8.2.3 Some Other GCN Coupled Metal Sulphide Photocatalysts 171
8.3 GCN Coupled Metal Oxide Heterojunctions for Environment Remediation 173
8.3.1 GCN and MoO3-Based Heterojunctions 177
8.3.2 GCN and Fe2O3-Based Heterojunctions 179
8.3.3 Some Other GCN Coupled Metal Oxide Photocatalysts 180
8.4 Conclusions and Outlook 181
References 181
9 2D Zeolites 193
Moumita Sardar, Manisha Maharana, Madhumita Manna and Sujit Sen
9.1 Introduction 193
9.1.1 What is 2D Zeolite? 195
9.1.2 Advancement in Zeolites to 2D Zeolite 196
9.2 Synthetic Method 197
9.2.1 Bottom-Up Method 197
9.2.2 Top-Down Method 198
9.2.3 Support-Assisted Method 199
9.2.4 Post-Synthesis Modification of 2D Zeolites 200
9.3 Properties 200
9.4 Applications 203
9.4.1 Petro-Chemistry 203
9.4.2 Biomass Conversion 203
9.4.2.1 Pyrolysis of Solid Biomass 203
9.4.2.2 Condensation Reactions 204
9.4.2.3 Isomerization 204
9.4.2.4 Dehydration Reactions 204
9.4.3 Oxidation Reactions 205
9.4.4 Fine Chemical Synthesis 206
9.4.5 Organometallics 206
9.5 Conclusion 206
References 207
10 2D Hollow Nanomaterials 211
S.S. Athira, V. Akhil, X. Joseph , J. Ashtami and P.V. Mohanan
10.1 Introduction 212
10.2 Structural Aspects of HNMs 213
10.3 Synthetic Approaches 214
10.3.1 Template-Based Strategies 215
10.3.1.1 Hard Templating 215
10.3.1.2 Soft Templating 217
10.3.2 Self-Templating Strategies 218
10.3.2.1 Surface Protected Etching 219
10.3.2.2 Ostwald Ripening 219
10.3.2.3 Kirkendall Effect 219
10.3.2.4 Galvanic Replacement 220
10.4 Medical Applications of HNMs 220
10.4.1 Imaging and Diagnosis Applications 221
10.4.2 Applications of Nanotube Arrays 222
10.4.2.1 Pharmacy and Medicine 224
10.4.2.2 Cancer Therapy 224
10.4.2.3 Immuno and Hyperthermia Therapy 226
10.4.2.4 Infection Therapy and Gene Therapy 226
10.4.3 Hollow Nanomaterials in Diagnostics and Therapeutics 227
10.4.4 Applications in Regenerative Medicine 227
10.4.5 Anti-Neurodegenerative Applications 228
10.4.6 Photothermal Therapy 229
10.4.7 Biosensors 230
10.5 Non-Medical Applications of HNMs 231
10.5.1 Catalytic Micro or Nanoreactors 231
10.5.2 Energy Storage 232
10.5.2.1 Lithium Ion Battery 232
10.5.2.2 Supercapacitor 232
10.5.3 Nanosensors 233
10.5.4 Wastewater Treatment 234
10.6 Toxicity of 2D HNMs 234
10.7 Future Challenges 237
10.8 Conclusion 239
Acknowledgement 240
References 240
11 2D Layered Double Hydroxides 249
J. Ashtami, X. Joseph, V. Akhil , S.S. Athira and P.V. Mohanan
11.1 Introduction 250
11.2 Structural Aspects 251
11.3 Synthesis of LDHs 252
11.3.1 Co-Precipitation Method 253
11.3.2 Urea Hydrolysis 254
11.3.3 Ion-Exchange Method 254
11.3.4 Reconstruction Method 254
11.3.5 Hydrothermal Method 255
11.3.6 Sol-Gel Method 255
11.4 Nonmedical Applications of LDH 255
11.4.1 Adsorbent 255
11.4.2 Catalyst 257
11.4.3 Sensors 260
11.4.4 Electrode 261
11.4.5 Polymer Additive 261
11.4.6 Anion Scavenger 262
11.4.7 Flame Retardant 263
11.5 Biomedical Applications 263
11.5.1 Biosensors 263
11.5.2 Scaffolds 265
11.5.3 Anti-Microbial Agents 266
11.5.4 Drug Delivery 267
11.5.5 Imaging 269
11.5.6 Protein Purification 269
11.5.7 Gene Delivery 270
11.6 Toxicity 272
11.7 Conclusion 273
Acknowledgement 274
References 274
12 Experimental Techniques for Layered Materials 283
Tariq Munir, Arslan Mahmood, Muhammad Imran, Muhammad Kashif, Amjad Sohail, Zeeshan Yaqoob, Aleena Manzoor and Fahad Shafiq
12.1 Introduction 284
12.2 Methods for Synthesis of Graphene Layered Materials 285
12.3 Selection of a Suitable Metallic Substrate 287
12.4 Graphene Synthesis by HFTCVD 287
12.5 Graphene Transfer 289
12.6 Characterization Techniques 291
12.6.1 X-Ray Diffraction Technique 291
12.6.2 Field Emission Scanning Electron Microscopy (FESEM) 292
12.6.3 Transmission Electron Microscopy (TEM) 293
12.6.4 Fourier Transform Infrared Radiation (FTIR) 294
12.6.5 UV-Visible Spectroscopy 295
12.6.6 Raman Spectroscopy 295
12.6.7 Low Energy Electron Microscopy (LEEM) 296
12.7 Potential Applications of Graphene and Derived Materials 297
12.8 Conclusion 298
Acknowledgement 298
References 299
13 Two-Dimensional Hexagonal Boron Nitride and Borophenes 303
Atif Suhail and Indranil Lahiri
13.1 Two-Dimensional Hexagonal Boron Nitride (2D h-BN): An Introduction 304
13.2 Properties of 2D h-BN 305
13.2.1 Structural Properties 305
13.2.2 Electronic and Dielectric Properties 306
13.2.3 Optical Properties 307
13.3 Synthesis Methods of 2D h-BN 308
13.3.1 Mechanical Exfoliation 309
13.3.2 Liquid Exfoliation 310
13.3.3 Chemical Vapor Deposition (CVD) 310
13.3.3.1 Synthesis Parameters 312
13.3.3.2 Growth Mechanism 313
13.3.3.3 Transfer of 2D h-BN Onto Other Substrates 314
13.3.4 Physical Vapor Deposition Method (PVD) 315
13.3.5 Surface Segregation Method 316
13.4 Application of 2D h-BN 317
13.4.1 2D h-BN in Electronic Manufacturing 318
13.4.2 2D h-BN as a Filler in Polymer Composites 319
13.4.3 2D h-BN as a Protective Barrier 320
13.4.4 2D h-BN in Optoelectronics 321
13.5 Borophene 323
13.5.1 Theoretical Investigation and Experimental Synthesis 324
13.5.2 Properties and Application of Borophene 326
13.5.2.1 Electronic Properties of Borophene 326
13.5.2.2 Chemical Properties 326
13.5.3 Potential Applications of Borophene 328
References 328
14 Transition-Metal Dichalcogenides for Photoelectrochemical Hydrogen Evolution Reaction 337
Rozan Mohamad Yunus, Mohd Nur Ikhmal Salehmin and Nurul Nabila Rosman
14.1 Introduction 337
14.2 TMDC-Based Photoactive Materials for HER 339
14.2.1 MoS2 339
14.2.2 MoSe2 341
14.2.3 WS2 341
14.2.4 CoSe2 342
14.2.5 FeS2 343
14.2.6 NiSe2 344
14.3 TMDCs Fabrication Methods 345
14.3.1 Hydrothermal 345
14.3.2 Chemical Vapor Deposition/Vapor Phase Growth Process 346
14.3.3 Metal-Organic Chemical Vapor Deposition (MOCVD) 347
14.3.4 Atomic Layer Deposition (ALD) 348
14.4 Current Photocatalytic Activity Performance 350
14.5 Summary and Perspective 351
References 352
15 State-of-the-Art and Perspective of Layered Materials 363
Tariq Munir, Muhammad Kashif, Aamir Shahzad, Nadeem Nasir, Muhammad Imran, Nabeel Anjum and Arslan Mahmood
15.1 Introduction 363
15.2 State-of-the-Art and Future Perspective 364
15.2.1 Electronic Devices 365
15.2.2 Optoelectronic Devices 369
15.2.3 Energy Storage Devices 372
15.3 Conclusion 374
References 374
Index 379
1
2D Metal-Organic Frameworks
Fengxian Cao1╬, Jian Chen1╬, Qixun Xia1* and Xinglai Zhang2┼
1 Henan Key Laboratory of Materials on Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, China
2 Shenyang National Laboratory for Materials Science (SYNL), Institute of Metal Research (IMR), Chinese Academy of Sciences (CAS), Shenyang, China
Abstract
The metal organic framework (MOF) is a crystalline porous material formed of an inorganic metal ion or cluster and an organic ligand. The invention has the characteristics of large pore volume, high specific surface area, variable structures, and multiple functions. It was widely applied in the fields of gas storage, separation, catalysis, sensing, and biomedicine. The emergence of this kind of material, to a large extent, has provided opportunities for the common development of other disciplines. In this chapter, the recent research and development of MOFs materials, including the synthesis methods (sol-gel method, hydrothermal solvothermal method, and microwave synthesis, etc.), the development status, the applications, i.e., hydrogen storage, energy storage, gas adsorption, catalytic reaction, sensors, biomedical applications, and so on, and the research hotspots of MOFs will be addressed.
Keywords: MOF, biomedicine, gas storage, sensors, catalysis
1.1 Introduction
Amidst the highly porous materials, metal organic frameworks (MOFs) exhibited incomparable tunable and structural diversity. Furthermore, MOFs synchronously demonstrate porosity and excellent electrical conductivity, which are a burgeoning group of materials and provide a wide range of applications, for instance, energy storages, electrocatalytic oxidation, gas adsorption, biomedical [1-6]. The atomic-level control over molecular and supramolecular structure provided by MOFs gives the chance for exploiting some new materials for a variety of applications [7].
As a new type of porous inorganic-organic hybrid crystal material, MOFs materials have attracted extensive attention in chemistry, material, physics, and other fields. It combines the characteristics of inorganic and organic materials. It has a wide range of potential values in gas storage and separation, luminous, sensing, catalysis, magnetism, and other fields. When MOFS was made into membrane, the application of MOFs material in gas phase field was expanded. The gas separation application of MOFs extends from adsorption separation to membrane separation. By using the adjustable or modified characteristics of pore size, shape, and surface chemical properties of MOFs, MOFs material is endowed with better membrane separation performance for some light gas molecules. In addition, MOFs film extends the detection range of MOFs to gas, which can realize humidity detection and fluorescence detection of other gases or vapors. In these cases, the MOFs will play an important role in the generation, transmission, adsorption, and storage.
The objective of this chapter is to summary recent literature describing the progress of MOFs. We first review the technology about how to grow MOFs thin films, including sol-gel method, hydrothermal solvothermal method, and microwave synthesis, etc. Whereafter, we summarized the structural feature and physicochemical properties description of MOFs. Subsequent sections discuss the MOF films in various applications, including hydrogen storage, energy storage, gas adsorption, catalytic reaction, sensors, biomedical applications, and the like. Finally, we discuss some limitations of MOFs in practical application.
1.2 Synthesis Approaches
The synthesis of two-dimensional (2D) MOFs compounds materials is generally carried out by cultivating single crystals. X-ray single crystal structure analysis is the most important method to determine the structure of metallic organic skeleton materials [8]. The accurate molecular structure of organometallic skeleton materials can be obtained by analysis. At present, the methods of synthesizing organometallic skeleton materials reported in the literature mainly include solution volatilization method, diffusion method, and hydrothermal/solvothermal synthesis route. These methods complement each other and sometimes use different synthesis methods or the same method and different conditions to obtain materials with different structures and functions [9]. With the development of collocation chemistry and material chemistry, ultrasonic synthesis, ion-liquid method, solid phase reaction method, sublimation method, microwave synthesis, method and two-phase synthesis method have also been applied to the synthesis of MOFs materials. Various synthesis ways have their own advantages and disadvantages. Therefore, the choice of synthesis methods is very important for the synthesis of MOFs, and even affects its structure and properties.
1.2.1 Selection of Synthetic Raw Materials
When the synthesis of MOFs is started, it is important to maintain the integrity of skeleton looseness in addition to geometric factors. Therefore, it is necessary to find sufficient mild conditions to maintain the function and structure of the organic ligand, while having sufficient reactivity to establish the coordination bond between the metal and the organic [10].
First of all, the metal components are mainly transition metal ions, and most of the valence states used by Zn2+, Cu2+, Ni2+, Pd2+, Pt2+, Ru, and Co2+. Secondly, organic ligands should contain at least one multi-dentate functional group, such as CO2H, CS2H, NO2, SO3H, and PO3H. CO2H was more commonly used in multi-dentate functional groups, such as erephthalic acid (BDC), tribenzoic acid (BTC), oxalic acid, succinic acid, etc. The selection of suitable organic ligands can not only form MOFs with novel structure, but also produce special physical properties. In addition, solvents can dissolve and protonize ligands in the process of synthesis. Metal salt and most ligands are solid as solvent is needed to dissolve it. Before metal ions and ligands are coordinated, ligands (such as carboxylic acids) need to be deprotonized, so alkaline solvents are often used. At present, many deprotonated alkaloids are used as organic amines, such as triethylamine (TEA), N, N2 dimethyl formamide (DMF), N, N2 diethylamide (DEF), N2 methyl pyrrolidone. At the same time, they are good solvents. In recent years, there are gradually examples of deprotonation with strong bases such as sodium hydroxide. Sometimes, solvents can also coordinate with metal ions as ligands or form weak interactions with other ligands, such as hydrogen bonds, which can be excluded by heating and vacuum. Finally, in order to make the synthesized organometallic skeleton have ideal pores, it is necessary to select the appropriate template reagent. Template reagents are sometimes separate substances, sometimes the solvents used.
1.2.2 Solvent Volatility Method
Solvent volatility method is suitable for the metal salt and ligands with good solubility and the obtained products that have a poor solubility in the used solvent. If the solubility of the ligands is poor, the dissolution of the ligands can be promoted by proper heating, and the coordination reaction can also be accelerated. The crystallization of the obtained coordination products is precipitated in the process of cooling [10, 11].
Solvent volatilization method is the most traditional method to synthesize MOFs materials and the principle of this method is that the crystal precipitates from saturated solution by solvent volatilization or decreasing temperature, and slowing down the volatilization rate or cooling is beneficial to the cultivation of perfect crystal form [12]. Specifically, by dissolving the selected organic ligands and metal salts in the appropriate solvent and placing them at rest, waiting for their slow self-assembly to form complex crystals.
1.2.3 Diffusion Method
Diffusion method means that the metal salt organic ligands and solvents are mixed into solution in a certain proportion, put into a small glass bottle that is placed in a large bottle with deproteinized solvent, seal the bottle mouth of the large bottle, and then the crystal can be formed after a period of static setting. Diffusion methods can be divided into gas phase diffusion, liquid layer diffusion, and gel diffusion.
1.2.3.1 Gas Phase Diffusion
The gas phase diffusion method is to dissolve the selected organic ligands and metal salt in the appropriate solvent, and then cause the lazy volatile solvent or volatile alkaline substance (for the carboxylic acid ligand containing hydrogen protons) to diffuse into the solution to reduce the solubility of the obtained complex product or speed up the coordination reaction, so that the complex precipitates in the form of crystallization. The volatilization rate of volatile solvents or alkaline substances in gas phase diffusion method will affect the nucleation speed of the complexes, and then affect the quality of precipitated crystals.
1.2.3.2 Liquid Phase Diffusion
The liquid phase diffusion method is to dissolve the selected organic ligands and metal salt in different solvents, and then put the seed solution on top of the other solution, or add another solvent to the interface of the two layers of solution that can slow down the diffusion rate. The reactant diffuses slowly and reacts in the solvent, and the reaction product precipitates in the form of crystal. The diffusion rate of reactants in liquid phase diffusion method will...
