MXenes : From Discovery to Applications of Two-Dimensional Metal Carbides and Nitrides

Since their discovery in 2011, MXenes (2D carbides, nitrides, and carbonitrides of early transition metals) have developed into one of the largest and most intensively studied families of 2D materials. They offer unique properties and are being explored in a large variety of applications. This book compiles the most important research from a pioneer of the field, Professor Yury Gogotsi, and his interdisciplinary research team, as well as numerous collaborators worldwide. It reports on the discovery and rise of MXenes and describes their synthesis and processing, properties, and incorporation into polymer, ceramic, and metal matrices to produce composites. It also discusses the potential of MXenes for use in energy storage, optics, electronics, and sensing, as well as biomedical, environmental, and electrocatalysis applications. The book will appeal to anyone interested in nanomaterials and their synthesis, properties, and applications. Cover Half Title Title Page Copyright Page Table of Contents Preface Part I: Introduction Chapter 1: The Rise of MXenes Part II: Discovery Chapter 2: Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2 Chapter 3: Two-Dimensional Transition Metal Carbides 3.1: Introduction 3.2: Results and Discussion 3.2.1: Ti2AlC 3.2.2: Ta4AlC3 3.2.3: TiNbAlC and (V0.5,Cr0.5)3AlC2 3.2.4: Ti3AlCN 3.3: Conclusions 3.4: Materials and Methods 3.4.1: Synthesis of MAX Phases and Exfoliation into MXenes 3.4.2: Characterization Chapter 4: Two-Dimensional, Ordered, Double Transition Metals Carbides 4.1: Introduction 4.2: Results and Discussion 4.2.1: Theoretical Prediction of Double Transition Metal MXenes 4.2.2: Synthesis of Double Transition Metal MXenes 4.2.3: Electrochemistry of Mo2TiC2Tx 4.3: Conclusions 4.4: Materials and Methods 4.4.1: Synthesis of MAX Phases 4.4.2: Synthesis of MXenes 4.4.3:Preparation and Testing of LIB Electrodes 4.4.4: Delamination of Mo2TiC2Tx and Preparation of MXene ‘Paper’ 4.4.5: Electrochemical Capacitor Fabrication and Testing 4.4.6: Microstructural Characterization 4.4.7: Density Functional Theory Simulations Chapter 5: Synthesis of Two-Dimensional Titanium Nitride Ti4N3 (MXene) Chapter 6: Synthesis of Mo4VAlC4 MAX Phase and Two-Dimensional Mo4VC4 MXene with Five Atomic Layers of Transition Metals 6.1: Introduction 6.2: Results and Discussion 6.2.1: Synthesis and Structural Characterization 6.2.2: Microscopy 6.2.3: Compositional Characterization 6.2.4: Thermal Analysis 6.2.5: Electrical and Optical Properties 6.2.6: Density Functional Theory 6.3: Conclusions 6.4: Experimental Methods 6.4.1: Synthesis of Mo4VAlC4 MAX 6.4.2: Synthesis of Mo4VC4 MXene 6.4.3: Mo4VC4 Film Preparation 6.4.4: Structural Characterization 6.4.5: Microscopy 6.4.6: Compositional Characterization 6.4.7: Optical Properties 6.4.8: Electrical Properties 6.4.9: Thermal Analysis 6.4.10: Density Functional Theory Calculations Part III: Properties Chapter 7. Electronic and Optical Properties of 2D Transition Metal Carbides and Nitrides 7.1: Introduction 7.2: Synthesis and Processing 7.3: Structure and Surface Chemistry 7.4: Computational Studies of Electronic Properties 7.5: Experimental Measurements of Electronic and Transport Properties 7.6: Effects of Surface Terminations on Electronic Properties 7.7: Electromagnetic Interference Shielding Properties 7.8: Sensors 7.8.1: Pressure and Strain Sensors 7.8.2: Molecular Sensing 7.9: MXene Heterostructures 7.10: Optoelectronic Properties: Transparent Conductive Thin Films 7.11: Nonlinear Optical Properties 7.12: Plasmonic Properties 7.13: Light-to-Heat Conversion and Photothermal Therapy Applications 7.14: Conclusions and Perspectives Chapter 8: Elastic Properties of 2D Ti3C2Tx MXene Monolayers and Bilayers 8.1: Introduction 8.2: Results 8.3: Discussion 8.4: Materials and Methods 8.4.1: Synthesis of Ti3C2Tx 8.4.2: Materials Characterization 8.4.2.1: Scanning electron microscopy 8.4.2.2: Atomic force microscopy 8.4.3: Analysis of Force-Indentation Curves Chapter 9: Control of MXenes’ Electronic Properties through Termination and Intercalation 9.1: Introduction 9.2: Results 9.2.1: Sample Synthesis and Experimental Approach 9.2.2: Adsorbed Species 9.2.3: Intercalation 9.2.4: Termination 9.3: Discussion 9.4: Methods 9.4.1: Syntheses of MXenes 9.4.2: Electron Microscopy and Spectroscopy 9.4.3: In situ Heating and Biasing 9.4.4: Thermogravimetric-Mass Spectrometry Analysis 9.4.5: Low Temperature Electronic Transport 9.4.6: X-ray Photoelectron Spectroscopy 9.4.7: X-ray Diffraction Chapter 10: High-Temperature Behavior and Surface Chemistry of Carbide MXenes Studied by Thermal Analysis 10.1: Introduction 10.2: Results and Discussion 10.2.1: Ti3C2Tx Etched in HF of Different Concentrations 10.2.2: Ti3C2Tx Etched in Mixed Acids 10.2.3: Ti3C2Tx Films 10.2.4: M2CTx MXenes: Mo2CTx and Nb2CTx 10.2.5: Mo2CTx and Nb2CTx Films 10.2.6: Chemical and Thermal Stability Implications 10.3: Summary 10.4: Experimental Section 10.4.1: Synthesis of Ti3C2Tx and Fabrication of Ti3C2Tx Film 10.4.2: Synthesis of Ti3C2Tx Using HF/H2SO4 or HF/HCl 10.4.3: Synthesis of Mo2CTx Multilayer Powder and 2D Mo2CTx Film 10.4.4: Synthesis of Nb2CTx Multilayer Powder and 2D Nb2CTx Film 10.4.5: Thermal Analysis−Mass Spectrometry (TA−MS) Chapter 11: Electrochromic Effect in Titanium Carbide MXene Thin Films Produced by Dip-Coating 11.1: Introduction 11.2: Results and Discussion 11.2.1: Thin Film Processing by Dip-Coating and Characterization 11.2.2: In Situ Electrochemical and Optical Characterization of Ti3C2Tx Thin Films 11.2.3: Understanding the Mechanism Involved in the Electrochromic Changes 11.3: Conclusions 11.4: Experimental Section Chapter 12: Effects of Synthesis and Processing on Optoelectronic Properties of Titanium Carbonitride MXene 12.1: Introduction 12.2: Experimental Section 12.3: Results and Discussion 12.3.1: Synthesis and Delamination 12.3.2: Optoelectronic Properties 12.3.3: Electronic and Transport Properties 12.4: Conclusions Chapter 13: Raman Spectroscopy Analysis of the Structure and Surface Chemistry of Ti3C2Tx MXene 13.1: Introduction 13.2: Results and Discussion 13.3: Conclusions 13.4: Materials 13.4.1: Raman Spectrometer Part IV: Synthesis and Processing Chapter 14: Intercalation and Delamination of Layered Carbides and Carbonitrides 14.1: Introduction 14.2: Results 14.2.1: Intercalation of MXenes 14.2.2: Molecular Dynamics (MD) Simulations 14.2.3: Delamination of MXene 14.2.4: Energy Storage Applications of Delaminated MXene 14.3: Discussion 14.4: Methods 14.4.1: Intercalation of f-MXene 14.4.2: De-intercalation of MXene 14.4.3: Delamination of MXene 14.4.4: Preparation of Pressed MXene Discs 14.4.5: Physical Characterization 14.4.6: Electrochemical Characterization 14.4.7: Preparation of Lithium Coin Cells 14.4.8: MD Simulations Chapter 15: Conductive Two-Dimensional Titanium Carbide ‘Clay’ with High Volumetric Capacitance Chapter 16: Amine-Assisted Delamination of Nb2C MXene for Li-Ion Energy Storage Devices Chapter 17: Guidelines for Synthesis and Processing of Two-Dimensional Titanium Carbide 17.1: Introduction 17.2: Discussion of Methods 17.2.1: General Synthesis and Processing of Ti3C2Tx MXene 17.2.2: Choice of Materials 17.2.2.1: Choice of Ti3AlC2 precursor 17.2.2.2: Choice of etchants and intercalants 17.2.3: Choice of the Synthesis Method 17.2.4: HF Etching Protocol 17.2.5: In situ HF Formation 17.2.6: Bifluoride-Based Etchants 17.2.7: Fluoride-Based Salt Etchants 17.2.8: Choice of Intercalation Method 17.2.9: Dimethyl Sulfoxide 17.2.10: Tetraalkylammonium Hydroxides 17.2.11: Lithium Ions 17.2.12: Processing, Deposition, and Storage 17.2.13: Sonication and Size Selection 17.2.14: Deposition of Flakes 17.2.15: Substrate Functionality 17.2.16: Storage of Material 17.2.17: Characterization Methods 17.3: Summary Chapter 18: Selective Etching of Silicon from Ti3SiC2 (MAX) to Obtain 2D Titanium Carbide (MXene) Chapter 19: Additive-Free MXene Inks and Direct Printing of Micro-Supercapacitors 19.1: Introduction 19.2: Results 19.2.1: Solvent Selection Criteria 19.2.2: Formulation of Inkjet-Printable MXene Organic Inks 19.2.3: All-MXene Inkjet-Printed Patterns 19.2.4: Extrusion Printing of All-MXene Patterns 19.2.5: Charge-Storage Performance of Printed MSCs 19.3: Discussion 19.4: Methods 19.4.1: Preparation of Ti3C2Tx Aqueous Inks 19.4.2: Preparation of Ti3C2Tx Organic Inks 19.4.3: Inkjet Printing of Micro-Supercapacitors and Resistors 19.4.4: Extrusion Printing of Micro-Supercapacitors 19.4.5: Materials Characterization 19.4.6: Electrochemical Characterization Chapter 20: Additive-Free MXene Liquid Crystals and Fibers 20.1: Introduction 20.2: Results 20.2.1: MXene Liquid Crystals 20.2.2: Pure LC MXene Fibers 20.2.3: Pure LC MXene Fiber Properties 20.3: Conclusion 20.4: Methods 20.4.1: Synthesis of Ti3C2 MXene 20.4.2: Preparation of L-Ti3C2 and S-Ti3C2 MXene Inks 20.4.3: Synthesis and Delamination of Mo2Ti2C3 and Ti2C MXenes Inks 20.4.4: Wet-Spinning of Pure MXene Fibers 20.4.5: Characterization Chapter 21: Scalable Manufacturing of Free-Standing, Strong Ti3C2Tx MXene Films with Outstanding Conductivity Chapter 22: Scalable Synthesis of Ti3C2Tx MXene 22.1: Introduction 22.2: Results and Discussion 22.3: Conclusion 22.4: Experimental Section Part V: Composites Chapter 23: Flexible and Conductive MXene Films and Nanocomposites with High Capacitance 23.1: Introduction 23.2: Results and Discussion 23.2.1: Conductive, Flexible, Free-Standing Ti3C2Tx Films 23.2.2: Conductive, Flexible, Free-Standing Ti3C2Tx/PDDA and Ti3C2Tx/PVA Composites 23.2.3: Mechanical Properties of the Ti3C2Tx and Ti3C2Tx/PVA Films 23.2.4: Capacitive Performance of Ti3C2Tx-Based Films 23.3: Conclusion 23.4: Materials and Methods 23.4.1: Preparation of MXene-Based Nanocomposites 23.4.2: Fabrication of Free-Standing Ti3C2Tx and Its Composite Films 23.4.3: Mechanical Testing 23.4.4: Electrochemical Testing Chapter 24: Flexible MXene/Graphene Films for Ultrafast Supercapacitors with Outstanding Volumetric Capacitance 24.1: Introduction 24.2: Results and Discussion 24.3: Conclusions 24.4: Experimental Section 24.4.1: Preparation of Delaminated Ti3C2Tx MXene Solution 24.4.2: Fabrication of Flexible MXene/rGO Hybrid Films 24.4.3: Material Characterizations 24.4.4: Electrochemical Measurements Chapter 25: Cold Sintered Ceramic Nanocomposites of 2D MXene and Zinc Oxide Chapter 26: Colloidal Gelation in Liquid Metals Enables Functional Nanocomposites of 2D Metal Carbides (MXenes) and Lightweight Metals 26.1: Introduction 26.2: Results and Discussion 26.2.1: Preparation and Exfoliation of MXene Sheets 26.2.2: Liquid Metals as Particle Dispersion Media 26.2.3: Colloidal Gelation in Liquid Metals 26.2.4: MXene/Mg−Li Composite 26.3: Conclusions 26.4: Methods 26.4.1: MXene Exfoliation via Minimally Intensive Layer Delamination 26.4.2: Intercalation with Tetramethylammonium Hydroxide 26.4.3: Mg−Li Alloy with Ti3C2Tx MXenes 26.4.4: Al-Doped Mg−Li Alloy with Ti3C2Tx MXenes 26.4.5: Ga Liquid Metal with Ti3C2Tx/TMA+ MXenes 26.4.6: Rheology Measurements 26.4.7: Mechanical Testing 26.4.8: Synchrotron X-ray Diffraction 26.4.9: Transmission Electron Microscopy 26.4.10: Focused Ion Beam-Scanning Electron Microscopy Part VI: Energy Storage Chapter 27: MXene: A Promising Transition Metal Carbide Anode for Lithium-Ion Batteries 27.1: Introduction 27.2: Experiment 27.2.1: Synthesis of Exfoliated Ti2C 27.2.2: Characterization 27.2.3: Electrochemical Testing 27.3: Results and Discussions 27.4: Conclusions Chapter 28: Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide Chapter 29: 2D Metal Carbides and Nitrides (MXenes) for Energy Storage 29.1: Introduction 29.2: Synthesis of MXenes 29.2.1: Etching with Hydrofluoric Acid 29.2.3: Delamination 29.2.2: Etching in the Presence of a Fluoride Salt 29.3: Structure and Properties 29.3.1: Structure of the MXene Layer 29.3.2: Surface Terminations 29.3.3: Effect of Synthesis Conditions on MXene Quality and Terminations 29.3.4: Stability 29.3.5: Physical and Mechanical Properties 29.4: Energy Storage Applications of 2D Carbides 29.4.1: MXenes in Batteries 29.4.2: MXene-Based Electrochemical Capacitors 29.5: Applications other than Energy Storage 29.6: Conclusions 29.7: Gaps in the Current Knowledge Chapter 30: Ultra-High-Rate Pseudocapacitive Energy Storage in Two-Dimensional Transition Metal Carbides 30.1: Introduction 30.2: Theoretical Capacitance and Voltage Window 30.3: Electrode Design for High Volumetric Performance 30.4: Electrode Design for High-Rate Performance 30.5: Conclusions 30.6: Methods 30.6.1: Synthesis of Ti3C2Tx 30.6.2: Synthesis of Mo2CTx 30.6.3: Preparation of Ti3C2 ‘Paper’ Electrodes 30.6.4: Preparation of Macroporous MXene Electrodes 30.6.5: Preparation of Ti3C2Tx Hydrogels 30.6.6: Electrochemical Measurements 30.6.7: Capacitance Calculations 30.6.8: Characterization of Structure and Properties 30.6.9: Characterization of Macroporous Electrodes 30.6.10: Processing Control for Hydrogel Films Chapter 31: Thickness-Independent Capacitance of Vertically Aligned Liquid-Crystalline MXenes Chapter 32: High Capacity Silicon Anodes Enabled by MXene Viscous Aqueous Ink 32.1: Introduction 32.2: Results and Discussion 32.2.1: MXene Ink Characterization 32.2.2: Electrode Fabrication and Characterization 32.2.3: Electrical and Mechanical Characterization 32.2.4: Electrochemical Characterization of nSi/MXene Anodes 32.2.5: Performance of Gr-Si/MX-C Anode 32.2.6: Comparison with Published Data 32.3: Conclusion 32.4: Methods 32.4.1: MXene Ink Preparation 32.4.2: Electrode Fabrication 32.4.3: Material Characterization 32.4.4: Electrochemical Characterization Chapter 33: Influences from Solvents on Charge Storage in Titanium Carbide MXenes 33.1: Introduction 33.2: Distinct Charging Processes for Different Solvent Systems 33.3: Molecular Arrangements of Electrolytes in MXenes 33.4: Full Desolvation towards Enhanced Energy Storage in MXene 33.5: Conclusions 33.6: Methods 33.6.1: Preparation of Ti3C2 Colloidal Solution 33.6.2: Preparation of Vacuum-Filtered Ti3C2 Thin Film 33.6.3: Preparation of Macroporous Ti3C2 33.6.4: Preparation of Graphene–CNT Composites for Positive Electrode 33.6.5: Material Characterization 33.6.6: Electrode Preparation 33.6.7: Electrochemical Tests 33.6.8: Calculations for the Electrochemical Tests 33.6.9: MD Simulations Part VII: Biomedical, Environmental, and Catalytic Applications Chapter 34: Charge- and Size-Selective Ion Sieving through Ti3C2Tx MXene Membranes Chapter 35: Single Platinum Atoms Immobilized on an MXene as an Efficient Catalyst for the Hydrogen Evolution Reaction 35.1: Introduction 35.2: Results 35.2.1: Synthesis and Structural Characterization of Mo2TiC2Tx–PtSA 35.2.2: Electronic States of Atoms in Mo2TiC2Tx–PtSA 35.2.3: Mechanistic Study on Electrochemical Exfoliation and Pt Single-Atom Immobilization 35.2.4: Electrochemical HER Evaluation of Mo2TiC2Tx–PtSA 35.2.5: DFT Calculation of Mo2TiC2O2–PtSA towards HER 35.3: Conclusions 35.4: Methods 35.4.1: Synthesis of Mo2TiC2Tx MXene 35.4.2: Delamination of Mo2TiC2Tx MXene Using Organic Solvent 35.4.3: Synthesis of Mo2TiC2Tx–VMo 35.4.4: Synthesis of Mo2TiC2Tx–PtSA 35.4.5: Characterization 35.4.6: Electrochemical Measurements 35.4.7: DFT Calculations Chapter 36: MXene Molecular Sieving Membranes for Highly Efficient Gas Separation 36.1: Introduction 36.2: Results 36.2.1: Preparation of MXene Nanosheets 36.2.2: Preparation of 2D MXene Membranes 36.2.3: Gas Separation Performance of 2D MXene Membranes 36.2.4: Gas Separation Mechanism 36.3: Discussion 36.4: Methods 36.4.1: Preparation of the MXene Membranes 36.4.2: Characterization of the MXene Nanosheets and Membranes 36.4.3: Gas Permeation Measurements 36.4.4: MD Simulations Chapter 37: MXene Sorbents for Removal of Urea from Dialysate: A Step toward the Wearable Artificial Kidney 37.1: Introduction 37.2: Results and Discussion 37.2.1: Interaction between Urea and MXenes 37.2.2: Urea Adsorption from Aqueous Solution 37.2.3: Urea Adsorption from Dialysate 37.2.4: Assessment of MXene Ti3C2Tx Biocompatibility 37.3: Conclusions 37.4: Experimental Section 37.4.1: Materials 37.4.2: Adsorption of Urea from Aqueous Solution 37.4.3: Adsorption of Urea from Dialysate Chapter 38: A Gel-Free Ti3C2Tx-Based Electrode Array for High-Density, High-Resolution Surface Electromyography 38.1: Introduction 38.1.1: High-Density Surface Electromyography 38.1.2: Materials and Design Strategies for sEMG 38.1.3: Fabrication of Ti3C2Tx MXene HDsEMG Arrays 38.2: Results and Discussion 38.2.1: Impedance Measurements in Saline and on Human Skin 38.2.2: Baseline sEMG Recording 38.2.3: High-Resolution Mapping of Muscle Activation 38.3: Conclusion 38.4: Experimental Section 38.4.1: Ti3C2Tx HDsEMG Array Fabrication 38.4.2: Impedance Spectroscopy 38.4.3: Testing the Effects of Skin Treatment on Skin Impedance 38.4.4: sEMG Recordings 38.4.5: sEMG Analysis Part VIII: Applications in Optics, Electronics and Sensing Chapter 39: Electromagnetic Interference Shielding with 2D Transition Metal Carbides Chapter 40: 2D Titanium Carbide (MXene) for Wireless Communication 40.1: Introduction 40.2: Results and Discussion 40.3: Materials and Methods 40.3.1: MXene Synthesis 40.3.2: Ti3C2 Spraying on PET 40.3.3: Measuring Sheet Resistance 40.3.4: Determining Thickness 40.3.5: Scanning Electron Microscopy 40.3.6: Atomic Force Microscopy 40.3.7: UV-vis Spectroscopy 40.3.8: X-ray Diffraction 40.3.9: Electrodynamic Simulations Chapter 41: Metallic Ti3C2Tx MXene Gas Sensors with Ultrahigh Signal-to-Noise Ratio 41.1: Introduction 41.2: Results and Discussion 41.3: Conclusions 41.4: Methods 41.4.1: Synthesis of Ti3C2Tx 41.4.2: Preparation of Black Phosphorus, MoS2, and Reduced Graphene Oxide Solutions 41.4.3: Ti3C2Tx, BP, MoS2, and RGO Film Fabrication and Transfer onto a Sensor Electrode 41.4.4: Gas Delivery System and Resistance Measurements 41.4.5: Noise Power Spectral Density (PSD) Measurements 41.4.6: Binding Energy Calculations via Density Functional Theories 41.4.7: Characterization Chapter 42: Surface-Modified Metallic Ti3C2Tx MXene as Electron Transport Layer for Planar Heterojunction Perovskite Solar Cells 42.1: Introduction 42.2: Results and Discussion 42.2.1: Characterization of Ti3C2Tx Nanosheets and UV-Ozone Treated Ti3C2Tx Films 42.2.2: Photovoltaic Characterization 42.3: Conclusion 42.4: Experimental Section 42.4.1: Materials 42.4.2: Preparation of Ti3C2Tx MXene Hydrocolloid 42.4.3: Preparation of Ti3C2Tx MXene Films 42.4.4: Device Fabrication 42.4.5: Thin Film Characterization 42.4.6: Device Characterization Chapter 43: Anomalous Absorption of Electromagnetic Waves by 2D Transition Metal Carbonitride Ti3CNTx Chapter 44: Beyond Ti3C2Tx: MXenes for Electromagnetic Interference Shielding 44.1: Introduction 44.2: Results and Discussion 44.3: Conclusions 44.4: Methods 44.4.1: Materials 44.4.2: Synthesis of MAX Powders 44.4.3: Synthesis of MXenes 44.4.3.1: Synthesis of Ti3C2Tx, Ti2CTx, and Ti3CNTx 44.4.3.2: Synthesis of Mo2TiC2Tx, Mo2Ti2C3Tx, and Nb4C3Tx 44.4.3.3: Synthesis of TiyNb2−yCTx 44.4.3.4: Synthesis of NbyV2−yCTx 44.4.4: Fabrication of MXene Films 44.4.4.1: Spin-casting 44.4.4.2: Spray-coating 44.4.4.3: Vacuum-assistant filtration 44.4.5: Characterization Index