Metal Oxide Nanosheets as 2D Building Blocks for the Design of Novel Materials

Melvin A Timmerman,Yang Wang,Johan E Ten Elshof,Phu T P Le,Rui Xia

doi:10.1002/chem.201905735

Abstract

Research into 2‐dimensional materials has soared during the last couple of years. Next to van der Waals type 2D materials such as graphene and h‐BN, less well‐known oxidic 2D equivalents also exist. Most 2D oxide nanosheets are derived from layered metal oxide phases, although few 2D oxide phases can be also made by bottom‐up solution syntheses. Owing to the strong electrostatic interactions within layered metal oxide crystals, a chemical process is usually needed to delaminate them into their 2D constituents. This Review article provides an overview of the synthesis of oxide nanosheets, and methods to assemble them into nanocomposites, mono‐ or multilayer films. In particular, the use of Langmuir–Blodgett methods to form monolayer films over large surface areas, and the emerging use of ink jet printing to form patterned functional films is emphasized. The utilization of nanosheets in various areas of technology, for example, electronics, energy storage and tribology, is illustrated, with special focus on their use as seed layers for epitaxial growth of thin films, and as electrochemically active electrodes for supercapacitors and Li ion batteries.

Highlights

A couple of advantages arises from the two-dimensional nature of nanosheets
The electrons are confined in a thin region.[3]. Their electrons are confined to a 2-dimensional lattice plane, which provides an ideal model system for fundamental studies in condensed matter physics, and for development of smallelectronic devices
This review provides a concise overview of the synthesis and processing of 2D metal oxide nanosheets into functional films, and gives some examples of their application in technological realms as diverse as nanoelectronics,[10] energy storage[11] and tribology,[12] with emphasis on but not limited to research done in our research group

Summary

Introduction

Functionalization, for example with graphene oxide, substitutional element doping, or strain and phase engineering.[8]. The structural similarities of graphene nanosheets to graphite may provide another type of intercalation anode compound.[81] MXenes have been attracting a great deal of attention as emerging low-cost and high energy-density anodes for batteries, for lithium, and for non-lithium batteries.[82] LiMPO4 (M = Fe, Mn, Co, Ni) has become of great interest as cathodes for next-generation high-power lithium ion batteries This is an olivine-type 2D material, which can be optimized by a solvothermal lithiation process to increase the lithium diffusion.[83] And leaf-like V2O5 nanosheets can be fabricated via a facile green approach as high energy cathode material.[84] Since nanosheets have a large surface to volume ratio, it is possible to attach functional groups on the nanosheet surface or dope the 2D sheets with foreign elements. Both hybrids showed good performance as high temperature solid lubricants (Figure 7 c), showing friction coefficients similar to that of the state-of-the-art material graphite (Figure 7 d)

Conclusions and Outlook

Findings

Conflict of interest