Preface

Chapter 8 **2D-Based Nanofluids: Materials Evaluation and**

Chapter 9 **Diverse Thermal Transport Properties of Two-Dimensional**

Chapter 10 **Mechanical Properties and Applications of Two-Dimensional**

Chapter 11 **Design, Assembly, and Fabrication of Two-Dimensional Nanomaterials into Functional Biomimetic**

Chengyi Hou, Minwei Zhang and Qijin Chi

**Materials: A Comparative Review 199**

Guangzhao Qin and Ming Hu

Rui Zhang and Rebecca Cheung

Jaime Taha-Tijerina, Laura Peña-Parás and Demófilo Maldonado-

**Performance 153**

**Materials 219**

**Device Systems 247**

Cortés

**VI** Contents

There are only few discoveries and new technologies in material science that have the poten‐ tial to dramatically alter and revolutionize our material world. Discovery of two-dimension‐ al (2D) materials, the thinnest form of materials to ever occur in nature, is one of them. After isolation of graphene from graphite in 2004, a whole other class of atomically thin materials, dominated by surface effects and showing completely unexpected and extraordinary prop‐ erties, has been created. Research on 2D materials, such as graphene and its cousins (sili‐ cene, germanene. phosphorene etc.), transition metal dichalcogenides (TMD), other layered semiconductors, MXenes, and so on, now involves thousands of researchers worldwide in the cutting-edge fields of physics, chemistry, engineering and biology, and extending from fundamental science to novel applications. The class of 2D materials possesses layered struc‐ ture with strong in-plane chemical bonds and weak out-of-plane coupling between layers. These layered structures provide the opportunity to be cleaved into individual freestanding atomic layers. When the thickness of layered material is reduced to a single or only a few layers, some extraordinary variations occur in their electronic properties due to quantum confinement. While identifying the uniqueness/individuality of the 2D materials, people may think that these layered materials will expose novel and unpredicted properties, allow‐ ing for many innovative openings.

The book "Two-dimensional Materials - Synthesis, Characterization and Potential Applica‐ tions" is meant to provide a comprehensive view and state-of-the-art knowledge about 2D materials. It consists of 11 chapters contributed by a team of experts in this exciting field and provides latest synthesis techniques, characterization of 2D materials and their potential ap‐ plications in energy conservation, electronics, optoelectronics, biotechnology, and so on.

Chapter 1 starts with an overview of the recent progress in the synthetic techniques for 2D materials, in which the authors introduce experimental scheme, advantages and disadvan‐ tages and applications of these synthetic strategies. Chapter 2 introduces the Langmuir-Blodgett Methodology, a versatile technique to build 2D material films including graphene oxides, quantum dots and silver nanowires. Chapter 3 presents the epitaxial growth of III-V nanowires and thin films on 2D layered materials.

2D TMDs have attracted considerable interest as alternatives to noble metal catalysts owing to their unique electronic structure and high catalytic activity. Chapter 4 provides an over‐ view of recent progress in 2D TMDs for electrocatalytic energy conversion applications. The presence of intrinsic defects in the form of vacancies and grain boundaries and extrinsic de‐ fects such as dopants in 2D materials results in new electronic states to endow unique func‐ tionalities. In this aspect, Chapter 5 presents the review of defect-induced phenomena in 2D materials for electronic and energy applications. Chapter 6 provides a comparative study between graphene against other 2D materials based on electronic applications. Chapter 7 discusses the recent achievements in the area of ultrafast fiber lasers utilizing 2D materials such as graphene, topological insulators, TMDs and black phosphorus.

Thermal energy management plays a crucial role from high-payload electrical instruments to ultrasmall electronic circuitries. The advent of nanofluids could successfully address the low thermal efficiency of conventional fluids in a significant manner. Chapter 8 narrates the advances in thermal nanofluids using 2D materials. Chapter 9 reviews the state-of-the-art theoretical and experimental investigations of phonon transport properties of broad 2D nanostructures. Special attention is given to the effect of different physical factors, such as sample size, strain and layer thickness.

By exploiting the unique mechanical and mechanoelectric transduction properties, 2D mate‐ rials can be used in a wide range of applications such as: flexible electronics, strain sensors, nanogenerators and innovative nanoelectromechanical systems (NEMS). In this aspect, the authors review mechanical properties of different 2D materials, varying from conductors, semiconductors to insulators in Chapter 10. In Chapter 11, the recent efforts on fabrication and assembly of 2D nanomaterials into functional biomimetic systems have been presented.

I hope that this book will be useful to a large number of researchers in various disciplines, both in academia and industry, seeking to gain update knowledge in the field of 2D materi‐ als.

I am very pleased to have gotten the opportunity to have served as the Editor of this book, which contains a wide variety of studies from authors all around the world. I would like to thank all the authors for their efforts in sending their best research papers to the attention of the audiences, including students, scientists and engineers, throughout the world.

I would also like to acknowledge the help given by InTech Open Access Publisher, in partic‐ ular, publishing process manager, Mr. Edi Lipović, for his assistance, patience and support throughout the whole process of this book project.

> **Dr. Pramoda Kumar Nayak** Low Dimensional Carbon Materials Centre, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
