A comparative study on the role of polyvinylpyrrolidone molecular weight on the functionalization of various carbon nanotubes and their composites

Polyvinylidene fluoride (PVDF) nanocomposites filled with polyvinylpyrrolidone (PVP) wrapped carbon nanotubes were prepared via a solution casting technique. The effect of the molecular weight (polymer chain length) of the PVP on the ability to wrap different nanotube structures and its impact towards nanotube dispersibility in the polymer matrix was explored. The study was conducted with PVP of four different molecular weights and nanotubes of three different structures. The composites that exhibit an effective nanotube dispersion lead to a nanotube network that facilitates improved thermal, electrical, and mechanical properties. It was observed that nanotubes of different structures exhibit stable dispersions in the polymer matrix though PVP functionalization of different molecular weights, but the key is achieving an effective nanotube dispersion at low PVP concentrations. This is observed in MWNT and AP-SWNT based composites with PVP of low molecular weight, leading to a thermal conductivity enhancement of 147% and 53%, respectively, while for P3-SWNT based composites, PVP of high molecular weight yields an enhancement of 25% in thermal conductivity compared to the non-functionalized CNT-PVDF composite. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Advances in Carbon Nanotube n-type Doping: Methods, Analysis and Applications

This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (Oct 2017) in accordance with the publisher’s archiving policyGreat advances in semiconductor technologies continue to be made with the demand for cheap, non-toxic, easily processed and environmentally friendly technologies on the rise. Single-walled carbon nanotubes (SWCNTs) are viewed as a promising candidate that satisfies these criteria however proper doping of the SWCNTs to provide n-type behaviour has been a persistent issue. In recent years, great advances have been made in providing air stable and efficient n-type doping of SWCNTs. This review presents the most recent and promising methods of n-type doping SWCNTs highlighted for their simplicity and quality of electrical properties. The analysis and major applications of these semiconductors with a focus on thermoelectric devices and transistors are discussed

Preparation of carbon surfaces for sensing applications via plasma hydrogenation

[Canberra, ACT

Electronic Spectra of Benzene: An APCELL Experiment

Australi

Solution processed graphene–silicon Schottky junction solar cells

Here, surfactant-assisted exfoliated graphene (SAEG) has been used to make transparent conducting graphene films which for the first time were used to make SAEG–silicon Schottky junctions for photovoltaics. The graphene films were characterised using UV-Vis spectroscopy, Raman spectroscopy, atomic force microscopy and four point probe sheet resistance measurements. The effects of film thickness, thermal annealing and chemical doping of the graphene films on the power conversion efficiency (PCE) of the cells were investigated. Mild annealing of thickness optimised films resulted in a doubling of the PCE. Additionally, chemical doping resulted in a further 300% increase of the peak PCE. These results indicate that SAEG has the potential to compete with chemical vapour deposited graphene in graphene–silicon Schottky junction applications.This work was supported by the Australian Microscopy and Microanalysis Research Facility (AMMRF). This work was also performed in part at the Flinders University node of the Australian National Fabrication Facility, a company established under the National Collaborative Research Infrastructure Strategy to provide nano- and micro-fabrication facilities for Australia's researchers

Transition from single to multi-walled carbon nanotubes grown by inductively coupled plasma enhanced chemical vapor deposition

In this work a simple and up-scalable technique for creating arrays of high purity carbon nanotubes via plasma enhanced chemical vapor deposition is demonstrated. Inductively coupled plasma enhanced chemical vapor deposition was used with methane and argon mixtures to grow arrays in a repeatable and controllable way. Changing the growth conditions such as temperature and growth time led to a transition between single and multi-walled carbon nanotubes and was investigated. This transition from single to multi-walled carbon nanotubes is attributed to a decrease in catalytic activity with time due to amorphous carbon deposition combined with a higher susceptibility of single-walled nanotubes to plasma etching. Patterning of these arrays was achieved by physical masking during the iron catalyst deposition process. The low growth pressure of 100 mTorr and lack of reducing gas such as ammonia or hydrogen or alumina supporting layer further show this to be a simple yet versatile procedure. These arrays were then characterized using scanning electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was also observed that at high temperature (550 °C) single-walled nanotube growth was preferential while lower temperatures (450 °C) produced mainly multi-walled arrays

Plasmonic Gold Nanostars Incorporated into High-Efficiency Perovskite Solar Cells

Incorporating appropriate plasmonic nanostructures into photovoltaic (PV) systems is of great utility for enhancing photon absorption and thus improving device performance. Herein, the successful integration of plasmonic gold nanostars (AuNSs) into mesoporous TiO2 photoelectrodes for perovskite solar cells (PSCs) is reported. The PSCs fabricated with TiO2-AuNSs photoelectrodes exhibited a device efficiency of up to 17.72 %, whereas the control cells without AuNSs showed a maximum efficiency of 15.19 %. We attribute the origin of increased device performance to enhanced light absorption and suppressed charge recombination

Preparation of catalytic substrates with ordered size of iron nanoparticles for production carbon nanotubes

Canberra, ACT, Australi

Heterojunction solar cells based on silicon and composite films of graphene oxide and carbon nanotubes

Graphene oxide (GO) sheets have been used as the surfactant to disperse single-walled carbon nanotubes (CNT) in water to prepare GO/CNT electrodes that are applied to silicon to form a heterojunction that can be used in solar cells. GO/CNT films with different ratios of the two components and with various thicknesses have been used as semitransparent electrodes, and the influence of both factors on the performance of the solar cell has been studied. The degradation rate of the GO/CNT-silicon devices under ambient conditions has also been explored. The influence of the film thickness on the device performance is related to the interplay of two competing factors, namely, sheet resistance and transmittance. CNTs help to improve the conductivity of the GO/CNT film, and GO is able to protect the silicon from oxidation in the atmosphere.This work is supported by the Australian Microscopy and Microanalysis Research Facility (AMMRF). We thank Professor Amanda Ellis (Flinders University, South Australia) for providing the GO

Gold nanotube membranes: fabrication of controlled pore geometries and tailored surface chemistries

This study concerns the fabrication, chemical modification and characterisation of gold nanotube membranes using porous alumina (PA) membranes as templates. Electroless deposition was used to finely coat membranes with gold, forming gold nanotubes within the pores. PA templates were fabricated with straight and shaped pores thus allowing the fabrication of a wide range of gold nanotube geometries. The gold deposition process provides control over the pore size of the membrane, where pore sizes can be reduced to molecular dimensions. Chemical sensitivity was introduced into the membrane through the addition of self assembled monolayers (SAMs) of thiols. Characterisation of thiol assembly within the pores of the membrane was investigated using confocal Raman