Alvin Orbaek White

Alvin Orbaek White
Swansea University | SWAN · College of Engineering

PhD Chemistry

About

36
Publications
6,975
Reads
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656
Citations
Additional affiliations
January 2014 - July 2016
Massachusetts Institute of Technology
Position
  • PostDoc Position
August 2007 - December 2013
Rice University
Position
  • PhD Student

Publications

Publications (36)
Article
Full-text available
Raman spectroscopy has been commonly used in materials science to detect chemicals. Based on inelastic scattering of light after incident photons interact with a molecule, it has high potential for non-destructive detection of specific contaminants in living biological specimens. The increasing use of carbon nanotubes (CNTs) increases its chance to...
Article
Full-text available
Carbon nanotubes (CNTs) have long been at the forefront of materials research, with applications ranging from composites for increased tensile strength in construction and sports equipment to transistor switches and solar cell electrodes in energy applications. There remains untapped potential still when it comes to energy and data transmission, wi...
Article
Full-text available
The inherent value and use of hydrocarbons from waste plastics and solvents can be extended through open-loop chemical recycling, as this process converts plastic to a range of non-plastic materials. This process is enhanced by first creating plastic–solvent combinations from multiple sources, which then are streamlined through a single process str...
Article
Full-text available
We report the effect of annealing, both electrical and by applied voltage, on the electrical conductivity of fibers spun from carbon nanotubes (CNTs). Commercial CNT fibers were used as part of a larger goal to better understand the factors that go into making a better electrical conductor from CNT fibers. A study of thermal annealing in a vacuum u...
Article
Full-text available
For every three people on the planet, there are approximately two Tonnes (Te) of plastic waste. We show that carbon recovery from polystyrene (PS) plastic is enhanced by the coaddition of solvents to grow carbon nanotubes (CNTs) by liquid injection chemical vapour deposition. Polystyrene was loaded up to 4 wt% in toluene and heated to 780 °C in the...
Preprint
The inherent value and use of hydrocarbon from waste plastics and solvents can be extended through open-loop chemical recycling as this process converts plastic to range of non-plastic materials. This process is enhanced by first creating plastic-solvent-combinations from multiple sources which are then streamlined through single process stream. We...
Preprint
Full-text available
For every three people on the planet there is approximately two Tonne (Te) of available plastic waste. We show that carbon recovery from polystyrene (PS) plastic is enhanced by the co-addition to solvents to grow carbon nanotubes (CNTs) by liquid injection chemical vapour deposition. Polystyrene was loaded up to 4 wt% in toluene and heated to 780 °...
Article
Optimised ZnO nanorod characteristics are essential for novel devices to operate efficiently, especially shifting the n-type nature towards intrinsic or p-type. The effects of argon bombardment for varying amounts of time on the surface chemistry and Fermi level of ZnO nanorods have been studied using XPS. Bombardment at 5 keV removed surface conta...
Article
Full-text available
Carbon nanotubes (CNTs) can be spun into fibers as potential lightweight replacements for copper in electrical current transmission since lightweight CNT fibers weigh <1/6th that of an equivalently dimensioned copper wire. Experimentally, it has been shown that the electrical resistance of CNT fibers increases with longitudinal strain; however, alt...
Article
Multi-walled carbon nanotubes (MWCNTs) grown by chemical vapor deposition retain the residual catalyst particles from which the growth occurred, which are considered a detriment to MWCNTs’ performance, especially electrical conductivity. The first direct measurements have been made of the electrical transport through the catalyst cap into the MWCNT...
Article
Multi-walled carbon nanotubes (MWCNTs) show an oscillation in electrical resistance (from I-V measurements) during mechanical distortion in which the peak separation is inversely correlated with the diameter of the MWCNTs. These results are the first experimental support of theoretical prediction that distortion causes the Van Hove singularities in...
Article
Full-text available
A new and environmentally friendly non-caustic route to synthesize ultramicroporous carbon spheres (CS) via a simple one-step non-catalytic and activation-free chemical vapor deposition (CVD) method is described. The CVD method was applied at different temperatures, 600-900 °C; 800 °C was identified as the optimum for CS formation using a safe soli...
Article
Herein we present an experimental/computational approach to probing the interaction between metal contacts and carbon nanotubes (CNTs) with regard creating the most efficient, low resistance, junction. Tungsten probes have been coated with copper or chromium and the efficiency of nano contact transport into multi-walled carbon nanotubes (MWCNTs) ha...
Article
Full-text available
Measurement of the angular and overlap dependence of the conduction between two identical carbon nanotubes (CNTs), with the same diameter and chirality, has only been possible through theoretical calculations; however, our observation of increased resistance adjacent to the junction between two CNTs facilitates such measurements. Since electrical r...
Article
Full-text available
The global plastics crisis has recently focused scientists’ attention on finding technical solutions for the ever-increasing oversupply of plastic waste. Black plastic is one of the greatest contributors to landfill waste, because it cannot be sorted using industrial practices based on optical reflection. However, it can be readily upcycled into ca...
Article
Despite extensive academic and commercial development, a comprehensive understanding of the principles necessary for high-yield production of carbon nanotubes (CNTs) is lacking, whether in oriented films, bulk powders, or other forms. In chemical vapor deposition growth of CNT films on substrates, trace contaminants of carbon, such as deposits on t...
Article
Two-point probe and Raman spectroscopy have been used to investigate the effects of vacuum annealing and argon bombardment, on the conduction characteristics of MWCNTs. Surface contamination has a large effect on the two-point probe conductivity measurements resulting in inconsistent and non-reproducible contacts as well as enhancing the electric f...
Article
Consistent synthesis of carbon nanotubes (CNTs) using laboratory-scale methods is essential to the development of commercial applications, particularly with respect to the verification of recipes that achieve control of CNT diameter, chirality, alignment, and density. Here, we report that, transients in the moisture level and carbon concentration d...
Article
Full-text available
Liquid crystalline polymers have recently been engineered to exhibit complex macroscopic shape adaptivity, including optically- and thermally- driven bending, self-sustaining oscillation, torsional motion, and three dimensional folding. Miniaturization of these novel materials is of great interest for both fundamental study of processing conditions...
Article
Full-text available
It is theorized that enhanced thermal heating may result from exposing single-walled carbon nanotubes (SWNTs) embedded in a conductive host to radiofrequency (RF) electric fields. We examine the RF-induced (13.56 MHz) heating behaviors of 95% metallic- and semiconducting-enriched SWNTs (m-/s-SWNTs) suspended in aqueous solutions with varying NaCl m...
Article
Full-text available
The aim of this simple, quick, and safe laboratory exercise is to provide undergraduate students an introduction to nanotechnology using nanoparticle (NP) synthesis. Students are provided two procedures that allow for the synthesis of different yet controlled sizes of silver NPs. After preparing the NPs, the students perform UV–visible spectroscopy...
Article
Full-text available
Ferrocene was used as a catalyst in a hydrocarbon solution to carry out injection chemical vapour deposition (CVD) growth of carbon nanomaterials in a horizontal tube furnace. The presence and quality of various carbon materials was determined using Raman spectroscopy, thermogravimetric analysis, and electron microscopy. Products ranged from amorph...
Article
Full-text available
High quality single-walled carbon nanotubes (SWNTs) were obtained following a new purification procedure, based on using Cl2 gas at high temperature. Cl2-treated SWNTs were fluorinated and modified with branched polyethyleneimine (PEI) to afford covalently functionalised PEI–SWNTs, which were then tested for cytotoxicity both in vitro (HPNE and BxP...
Article
Full-text available
Vertical arrays of single walled carbon nanotubes (VA-SWNTs) were grown using bi-metallic nanoparticle pro-catalysts. Iron oxide particles were doped with varying quantities of first row transition metals (Mn, Co, Ni, and Cu) for a comparative study of the growth of nanotubes. VA-CNT samples were verified using scanning electron microscopy, and cha...
Article
Full-text available
Binary (M1−M2−O) and ternary (M1−M2−M3−O) metal-oxide nanoparticles (NPs) have been prepared by thermal decomposition in benzyl ether of the appropriate M(acac) n (M = Fe, Mn, Pd, Cu, Al, Gd) compounds in the presence of a mixture of oleic acid and oleylamine templating (surface capping) ligands, and 1,2-hexadecanediol as an accelerating agent. The...
Article
Quantification using scanning electron microscopy (SEM) of single walled carbon nanotubes (SWNTs) grown per unit area using a Co-Fe (50:50) catalyst system, prepared by the incorporation of the appropriate metal salts into a Spin-On Glass substrate, at 900°C. The effects of substrate, as well as catalyst precursor concentration, were investigated....
Article
Full-text available
Comparison of AFM and SEM images of single walled carbon nanotubes (SWNTs) grown within a dielectric matrix reveal subterranean nanotubes that are present within the matrix, and as such can be charge screened by the dielectric. Under adequate imaging conditions for the SWNT/silica sample the intensity of isolated nanotubes is found to be inversely...
Article
Full-text available
Quantifying nanoparticle (NP) transport within porous geological media is imperative in the design of tracers and sensors to monitor the environmental impact of hydraulic fracturing that has seen increasing concern over recent years, in particular the potential pollution and contamination of aquifers. The surface chemistry of a NP defining many of...
Article
Attempts at depositing uniform films of nanoparticles by drop-drying have been frustrated by the "coffee-stain" effect due to convective macroscopic flow into the contact line. Here, we show that uniform deposition of nanoparticles in aqueous suspensions can be attained easily by drying the droplet in an ethanol vapor atmosphere. This technique all...
Article
SEM quantification of SWNTs grown per unit area using a Co-Fe (50:50) catalyst system at 900°C were subjected to secondary growth, using a range of CH 4:H 2 ratios. It was found that nucleation and growth stages are optimal under different conditions. Optimum conditions for nucleation resulted in >10x increase in SWNT density. Optimization is depen...
Article
Single walled carbon nanotubes (SWNTs) seeds are grown using Fe-Co nanoparticles on spin-on-glass. The relative efficiency of nucleation and amplification (versus etching) was investigated as a function of the CH(4)/H(2) feedstock ratio and growth temperature. At 900 °C, maximum amplification is obtained with CH(4)/H(2) ratio of 80:20 but 60:40 for...
Article
Due to the unique physicochemical properties of nanomaterials (NM) and their unknown reactivity, the possibility of NM altering the optical properties of fluorometric/colorimetric probes that are used to measure their cyto- and genotoxicity may lead to inaccurate readings. This could have potential implications given that NM, such as ultrafine supe...
Article
A procedure for vertically aligned carbon nanotube (VA-CNT) production has been developed through liquid-phase deposition of alumoxanes (aluminum oxide hydroxides, boehmite) as a catalyst support. Through a simple spin-coating of alumoxane nanoparticles, uniform centimer-square thin film surfaces were coated and used as supports for subsequent depo...
Article
Self-assembled monolayers (SAMs) of iron oxide nanoparticles have been prepared using carboxylic-acid-terminated dendrimers. The iron-containing SAM was used as the catalyst for growth of vertical arrays of carbon nanotubes (CNTs). This approach has the potential for producing diameter controlled CNTs from premade catalyst nanoparticles as well as...
Technical Report
Micro-an-nanotechnology (MNT) is a rapidly advancing field of research with applications to benefit nearly all facets of society. At present is is unclear what role micro-and-nanotechnologies will play in the space sector as they continue to develop. We have surveyed the existing space applications of MNT, and from these applications three concept...

Questions

Question (1)
Question
I have been growing SWNT/MWNTs with a variety of hydrocarbons (gas and liquid), but have recently started working using ethanol, so I am curious to know the differences using this material.

Projects

Project (1)
Project
#MSc #research #jobopportunity. #KESS2 and .@SaltsHealthcare #funded in .@ESRI_Swansea to turn #plastics into #nanomaterials for #CircularEconomy for the #healthcare sector at the #SwanseaUni Bay Campus #Swansea. Deadline July 31st. ((https://tinyurl.com/clean-nano )) #ZeroPlasticWasteUK