Improved Photoelectrochemical Performance of MoS2 through Morphology-Controlled Chemical Vapor Deposition Growth on Graphene

The morphology of MoS2 nanostructures was manipulated from thin films to vertically aligned few-layer nanosheets on graphene, in a controllable and practical manner, using metalorganic chemical vapor deposition. The effects of graphene layer and MoS2 morphology on photoelectrochemical (PEC) performance were systematically studied on the basis of electronic structure and transitions, carrier dynamic behavior, and PEC measurements. The heterojunction quality of the graphene/vertical few-layer MoS2 nanosheets was ensured by low-temperature growth at 250−300 °C, resulting in significantly improved charge transfer properties. As a result, the PEC photocurrent density and photoconversion efficiency of the few-layer MoS2 nanosheets significantly increased upon the insertion of a graphene layer. Among the graphene/MoS2 samples, the few-layer MoS2 nanosheet samples exhibited shorter carrier lifetimes and smaller charge transfer resistances than the thin film samples, suggesting that vertically aligned nanosheets provide highly conductive edges as an efficient pathway for photo-generated carriers and have better electronic contact with graphene. In addition, the height of vertical MoS2 nanosheets on graphene should be controlled within the carrier diffusion length (~200 nm) to achieve the optimal PEC performance. These results can be utilized effectively to exploit the full potential of two-dimensional MoS2 for various PEC applications.

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Structure Controlled Synthesis of Vertically Aligned Carbon Nanotubes Using Thermal Chemical Vapor Deposition Process

Journal of Heat Transfer ◽

10.1115/1.4002443 ◽

2010 ◽

Vol 133 (3) ◽

Cited By ~ 12

Author(s):

Myung Gwan Hahm ◽

Young-Kyun Kwon ◽

Ahmed Busnaina ◽

Yung Joon Jung

Keyword(s):

Carbon Nanotubes ◽

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Large Scale ◽

Chemical Vapor ◽

Controlled Synthesis ◽

Full Potential ◽

Thermal Chemical Vapor Deposition ◽

Vertically Aligned ◽

Walled Carbon Nanotubes

Due to their unique one-dimensional nanostructure along with excellent mechanical, electrical, and optical properties, carbon nanotubes (CNTs) become a promising material for diverse nanotechnology applications. However, large-scale and structure controlled synthesis of CNTs still have many difficulties due to the lack of understanding of the fundamental growth mechanism of CNTs, as well as the difficulty of controlling atomic-scale physical and chemical reactions during the nanotube growth process. Especially, controlling the number of graphene wall, diameter, and chirality of CNTs are the most important issues that need to be solved to harness the full potential of CNTs. Here we report the large-scale selective synthesis of vertically aligned single walled carbon nanotubes (SWNTs) and double walled carbon nanotubes (DWNTs) by controlling the size of catalyst nanoparticles in the highly effective oxygen assisted thermal chemical vapor deposition (CVD) process. We also demonstrate a simple but powerful strategy for synthesizing ultrahigh density and diameter selected vertically aligned SWNTs through the precise control of carbon flow during a thermal CVD process.

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Vertically aligned growth of small-diameter single-walled carbon nanotubes on flexible stainless steels by alcohol catalytic chemical vapor deposition with Ir catalyst on alumina buffer layer

Japanese Journal of Applied Physics ◽

10.35848/1347-4065/ac3b01 ◽

2021 ◽

Author(s):

Shu KONDO ◽

Daiki YAMAMOTO ◽

Kamal Prasad Prasad Sharma ◽

Yazid Yaakob ◽

Takahiro SAIDA ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Buffer Layer ◽

Vapor Deposition ◽

Small Diameter ◽

Chemical Vapor ◽

Cost Effective ◽

Chemical Vapor Deposition Growth ◽

Catalytic Chemical Vapor Deposition ◽

Single Walled Carbon ◽

Vertically Aligned

Abstract We performed single-walled carbon nanotube (SWCNT) growth on flexible stainless-steel foils by applying alcohol catalytic chemical vapor deposition using an Ir catalyst with an alumina buffer layer. When the alumina thickness was 90 nm, vertically aligned SWCNTs with a thickness of 4.6 m were grown. In addition, Raman results showed that the diameters of most SWCNTs were distributed below 1.1 nm. Compared with conventional chemical vapor deposition growth where Si wafers are used as substrates, this method is more cost effective and easier to extend for mass production of small-diameter SWCNTs.

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Low-Temperature Chemical Vapor Deposition Growth of Graphene Layers on Copper Substrate Using Camphor Precursor

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.18862 ◽

2020 ◽

Vol 20 (12) ◽

pp. 7698-7704

Author(s):

K. Kavitha ◽

Akanksha R. Urade ◽

Gurjinder Kaur ◽

Indranil Lahiri

Keyword(s):

Chemical Vapor Deposition ◽

Low Temperature ◽

Vapor Deposition ◽

Graphene Layer ◽

Copper Substrate ◽

Chemical Vapor ◽

Large Area ◽

Chemical Vapor Deposition Growth ◽

Graphene Layers ◽

Grown Graphene

A two-step, low-temperature thermal chemical vapor deposition (CVD) process, which uses camphor for synthesizing continuous graphene layer on Cu substrate is reported. The growth process was performed at lower temperature (800 °C) using camphor as the source of carbon. A threezone CVD system was used for controlled heating of precursor, in order to obtain uniform graphene layer. As-grown samples were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The results show the presence of 4–5 layers of graphene. As-grown graphene transferred onto a glass substrate through a polymer-free wet-etching process, demonstrated transmittance ~91% in visible spectra. This process of synthesizing large area, 4–5 layer graphene at reduced temperature represents an energy-efficient method of producing graphene for possible applications in opto-electronic industry.

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