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2017 | Book

ZnO-Nanocarbon Core-Shell Type Hybrid Quantum Dots

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About this book

This book offers a comprehensive overview of ZnO-nano carbon core shell hybrid issues. There is significant interest in metal oxide/nanocarbon hybrid functional materials in the field of energy conversion and storage as electrode materials for supercapacitors, Li ion secondary battery, electrocatalysts for water splitting, and optoelectronic devices such as light emitting diodes and solar photovoltaic cells. Despite efforts to manipulate more uniform metal oxide-nanocarbon nanocomposite structures, they have shown poor performance because they are randomly scattered and non-uniformly attached to the nanocarbon surface. For higher and more effective performance of the hybrid structure, 3D conformal coating on metal oxides are highly desirable.

In the first part of the book, the physical and chemical properties of ZnO and nanocarbons and the state-of-the-art in related research are briefly summarized. In the next part, the 3D conformal coating synthetic processes of ZnO templated nanocarbon hybrid materials such as ZnO-graphene,-C60, single-walled (SWCNT) are introduced with the aid of schematic illustrations. Analysis of their chemical bonding and structure are also presented. In the final section, several applications are presented: UV photovoltaic cells and photoelectrochemical anodes for water splitting using ZnO-C60 and ZnO-graphene, white-light-emitting diodes based on ZnO-graphene quantum dots(GQDs), inverted solar cells using ligand-modified ZnO-graphene QDs, and P(VDF-TrFE) copolymer with mixed with nano-ring SWCNT.

The book describes how strong anchoring bonds between a ZnO core and carbon nanomaterial shell will ultimately prevail over the main drawbacks of ZnO with high charge recombination and poor electrochemical stability in liquid solutions. Due to the moderate energy states and excellent electric properties of the nanocarbons, ultrafast charge carrier transport from the ZnO core to the nanocarbon shell is guaranteed with the use of the photoluminescence (PL) lifetime measurement.

Given the growing interest and significance of future research in optoelectronic and electrochemical devices applications, the contents are very timely. This book is targeted towards researchers looking for highly efficient metal oxide-nanocarbon hybrid functional materials in the fields of nano-optoelectronics, photoelectrochemistry, energy storage and conversion.

Table of Contents

Frontmatter
Chapter 1. Introduction
Abstract
Huge amounts of metal oxide/nanocarbon nanocomposite have been synthesized by various methods and evaluated by fabricating optoelectronic devices, electrochemical devices, and energy storage devices etc. Despite many efforts to manipulate more uniform metal oxide-nanocarbon nanocomposite structures, the metal oxide nano particles were still randomly scattered and nonuniformly attached to the nanocarbon surfaces. Until now, consolidated core-shell structure metal-oxide NPs encircled by nanocarbons with high conformality have been rarely reported. In this book, the synthetic processes, analysis, and applications of unique consolidated core-shell strucutres of ZnO–nanocarbons (graphene, C60, CNTs) were introduced.
Won Kook Choi
Chapter 2. ZnO–Nanocarbons Core–Shell Hybrid Quantum Dots
Abstract
New functional nanoparticle of partially encircled ZnO–graphene (C60, CNTs) consolidated hybrid quantum dots with quasi-core–shell structure can be synthesized. The chemical reaction of embryonic ZnO inner QDs with oxygen-contained functional groups (epoxy, hydroxy, carbonyl, and carboxyl) at defect-like sites generated on acid-treated graphite powder surfaces plays a key role in the formation of hybrid structures. The product of this reaction was then washed in water and dried to obtain pure ZnO–graphene (C60, CNTs) quasi core–shell QDs.
Won Kook Choi
Chapter 3. Applications of ZnO–Nanocarbon Core–Shell Hybrid Quantum Dots
Abstract
In ZnO–graphene (–C60) based UV photovoltaic devices, the maximum PCE of 3.02 % for ZnO–C60 is greater than that of 2.33 % for ZnO–graphene QDs, which can be ascribed to difference in the energy level alignment of C60 and graphene with poly-TPD (hole transport layer) and Cs2CO3/Al(electron transport layer). The ZnO–graphene quantum-dot layer LED pixels shows uniform luminescence with the maximum blue luminance of 798 cd/m2 at 15 V. In the photoelectrochemical devices, the rate constant for ZnO was only 0.0088 and slightly increased to 0.053 for ZnO–graphene. ZnO–C60 shows a k value more than 10-times higher than that of bare ZnO because of the higher charge transportation property of ZnO–C60. The normalized photocurrent density to time curves demonstrate that the ZnO–graphene core–shell structures have more improved long-term stability performance than those of ZnO–C60 because 2-Dim graphene can conformally cover the surface of the ZnO QD core better than 0-Dim C60 can.
Won Kook Choi
Metadata
Title
ZnO-Nanocarbon Core-Shell Type Hybrid Quantum Dots
Author
Won Kook Choi
Copyright Year
2017
Publisher
Springer Singapore
Electronic ISBN
978-981-10-0980-8
Print ISBN
978-981-10-0979-2
DOI
https://doi.org/10.1007/978-981-10-0980-8

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