Preparation of carbon surfaces for sensing applications via plasma hydrogenation

[Canberra, ACT

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

Canberra, ACT, Australi

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

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

Field emission from single-, double-, and multi-walled carbon nanotubes chemically attached to silicon

The chemical attachment and field emission (FE) properties of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) chemically attached to a silicon substrate have been investigated. A high density of CNTs was revealed by atomic force microscopy imaging with orientation varying with CNT type. Raman spectroscopy was used to confirm the CNT type and diameter on the surfaces. The field emission properties of the surfaces were studied and both current-voltage and Fowler-Nordheim plots were obtained. The SWCNTs exhibited superior FE characteristics with a turn-on voltage (Eto) of 1.28 V μm−1 and electric field enhancement factor (β) of 5587. The DWCNT surface showed an Eto of 1.91 V μm−1 and a β of 4748, whereas the MWCNT surface exhibited an Eto of 2.79 V μm−1 and a β of 3069. The emission stability of each CNT type was investigated and it was found that SWCNTs produced the most stable emission. The differences between the FE characteristics and stability are explained in terms of the CNT diameter, vertical alignment, and crystallinity. The findings suggest that strength of substrate adhesion and CNT crystallinity play a major role in FE stability. Comparisons to other FE studies are made and the potential for device application is discussed

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

Water transport through nanoporous materials: Porous silicon and single walled carbon nanotubes

We report upon the pressure driven water transport through porous silicon (pSi) and single walled carbon nanotube (SWCNT) membranes. Fabrication of the membranes was monitored by AFM and SEM. Water permeability as high as 16926 mm3 cm-2 s-1 atm-1 is found for the pSi membrane. The SWCNT membrane is built upon the pSi membrane and a water permeability of 0.02 mm3 cm-2 s-1 atm-1 is achieved. Performance comparisons to similar CNT membranes are made and future improvements to the system are proposed

Pore spanning lipid bilayers on silanised nanoporous alumina membranes

http://spiedigitallibrary.org/journals/doc/SPIEDL-home/proc

Combined thermal and FTIR analysis of porous silicon based nano-energetic films

Nanoporous silicon (pSi) films on a silicon wafer were loaded with sodium perchlorate (SP) and perfluoropolyether (PFPE) oxidising agents to generate a pyrotechnic energetic material. The potentially violent reaction between the silicon and the loaded oxidising agent was studied using correlated differential scanning calorimetry (DSC) and FTIR spectroscopy for samples heated continuously between ambient and 500 degrees C. We observed that the energetic reaction between pSi and SP depended on the presence of various hydride species on the surface of freshly etched pSi, and on formation of volatile free radical species released during either oxidation of the surface in the presence of air at about 200 degrees C or during desorption of the hydride above 270 degrees C in the absence of oxygen. However, energetic reactions between pSi and PFPE were delayed until pyrolysis of the PFPE above 390 degrees C in the absence of oxygen, suggesting PFPE's suitability for pyrotechnics applications. Correlated thermal and spectroscopic methods of analysis gave new insights into the earliest stages of the reaction of these energetic materials