ORCID Profile
0000-0003-1414-928X
Current Organisation
UNSW
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Publisher: Wiley
Date: 12-09-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9TA11961B
Abstract: The present work reports a simple and rapid disassembly/reassembly approach at room temperature to tailor functional metal oxides of 2D and 3D architectures.
Publisher: IOP Publishing
Date: 02-05-2014
DOI: 10.1088/0957-4484/25/21/215705
Abstract: The composition of InxGa1 - xN nanorods grown by molecular beam epitaxy with nominal x = 0.5 has been mapped by electron microscopy using Z-contrast imaging and x-ray microanalysis. This shows a coherent and highly strained core-shell structure with a near-atomically sharp boundary between a Ga-rich shell (x ∼ 0.3) and an In-rich core (x ∼ 0.7), which itself has In- and Ga-rich platelets alternating along the growth axis. It is proposed that the shell and core regions are lateral and vertical growth sectors, with the core structure determined by spinodal decomposition.
Publisher: American Chemical Society (ACS)
Date: 07-02-2020
Publisher: American Chemical Society (ACS)
Date: 05-04-2021
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 11-2018
Publisher: American Chemical Society (ACS)
Date: 09-2023
Publisher: Wiley
Date: 02-09-2019
Publisher: IOP Publishing
Date: 29-11-2013
Publisher: Wiley
Date: 30-05-2019
Publisher: Elsevier BV
Date: 2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5TA08214E
Abstract: Crystals of earth-abundant tin disulfide exhibit high-surface-area platelet formation with ideal photocatalytic properties for water splitting in their ground state.
Publisher: IOP Publishing
Date: 15-10-2015
Publisher: MDPI AG
Date: 25-10-2022
DOI: 10.3390/MET12111808
Abstract: The effects of the combined addition of B and Ti, as well as the influence of different strain rates on the hot ductility behavior of low carbon, continuously cast, microalloyed steels were investigated in this work. Tensile tests, microstructure analyses, and thermokinetic simulations were performed with in situ melted s les. Furthermore, prior austenite grain evaluations were carried out for the two different microalloyed steels. Increasing the strain rate brought improvements to the ductility, which was more significant in the steel with the leanest composition. The steel containing more B and Ti presented a better hot ductility behavior under all conditions tested. The main causes for the improvements rely on the precipitation behavior and the austenite–ferrite phase transformation. The preferential formation of TiN instead of fine BN and AlN was seen to be beneficial to the ductility, as well as the absence of MnS. Grain boundary segregation of free B that did not form BN retarded the ferrite formation, avoiding the brittleness brought by the thin ferrite films at the austenite grain boundaries. Furthermore, it was revealed that for the steels in question, the prior austenite grains have less influence on the hot ductility behavior than the precipitates and ferrite formation.
Publisher: Elsevier BV
Date: 12-2013
Publisher: MDPI AG
Date: 27-05-2021
Abstract: Solution-processed iron selenide nanocrystals (NCs) have recently attracted considerable attention in electrocatalysis water splitting. Nevertheless, a primary challenge in current iron-based NCs chemical synthesis is controlling phase purities between each chalcogen (monochalcogenide, dichalcogenides, and oxides), which requires a comprehensive understanding of the reaction mechanisms at the early stages of nucleation. Herein, we investigate the fundamental steps in transforming molecular organoiron and organoselenium precursors to iron selenides NCs with the view of developing universal synthesis protocols for phase pure metal selenium and metal oxides NCs. The main intermediate species and volatile by-products are identified by high-resolution electron microscopy and Nuclear Magnetic Resonance (NMR) spectroscopy (1H, 13C, and 31P). Experimental evidence suggests that the phase determining factor is the coordinating reactivity difference between olefins (1-octadecene, oleylamine), tributylphosphine and trioctylphosphine associated with their corresponding Se bond cleavage. This work proposes organoselenium interconversion reaction mechanisms during iron selenides synthesis, offering a universal synthetic strategy for other electrocatalytically or photocatalytically active layered metal selenides materials.
Publisher: IOP Publishing
Date: 30-07-2018
Abstract: Two In
Publisher: Wiley
Date: 14-09-2021
Abstract: Ultrathin porphyrinic 2D MOFs, ZnTCPP nanosheets (TCPP: 5,10,15,20‐(tetra‐4‐carboxyphenyl) porphyrin) were employed as heterogeneous photocatalysts to activate PET‐RAFT polymerization under various wavelengths ranging from violet to orange light. High polymerization rates, oxygen tolerance, and precise temporal control were achieved. The polymers showed narrow molecular weight distributions and good chain‐end fidelity. The 2D ZnTCPP nanosheets were applied as photocatalysts in stereolithographic 3D printing in an open‐air environment under blue light to yield well‐defined 3D printed objects. Apart from providing an efficient catalytic system, 2D ZnTCPP nanosheets reinforced the mechanical properties of the 3D printed materials. The presence of ZnTCPP embedded in the materials conferred effective antimicrobial activity under visible light by production of singlet oxygen, affording 98 % and 93 % anti‐bacterial efficiency against Gram‐positive and Gram‐negative bacteria, respectively.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 12-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4NR03977G
Abstract: We report successful pulsed laser deposition of tungsten oxide nanorods on a range of metal substrates, and demonstrate striking substrate dependent differences in nanorod morphology.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TA00285G
Abstract: Trace amounts of AIBN substantially accelerate the homolytic cleavage of the Se–Se bond, facilitating the phosphine-free synthesis of CdSe quantum dots.
Publisher: Springer Science and Business Media LLC
Date: 11-10-2019
Publisher: Oxford University Press (OUP)
Date: 30-07-2021
Publisher: American Chemical Society (ACS)
Date: 03-10-2019
DOI: 10.1021/JACS.9B07659
Abstract: The direct growth of Pt islands on lattice mismatched Ni nanoparticles is a major synthetic challenge and a promising strategy to create highly strained Pt atoms for electrocatalysis. By using very mild reaction conditions, Pt islands with tunable strain were formed directly on Ni branched particles. The highly strained 1.9 nm Pt-island on branched Ni nanoparticles exhibited high specific activity and the highest mass activity for hydrogen evolution (HER) in a pH 13 electrolyte. These results show the ability to synthetically tune the size of the Pt islands to control the strain to give higher HER activity.
Publisher: American Chemical Society (ACS)
Date: 25-05-2022
Abstract: Gallium (Ga) compounds, as the source of Ga ions (Ga
Publisher: American Chemical Society (ACS)
Date: 31-05-2018
Abstract: LaAlO
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SE00038K
Abstract: Electron microscopy (EM), specifically in situ , is a powerful analytical and characterisation technique that is widely used to study electrode materials for battery applications.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-12-2018
DOI: 10.1212/WNL.0000000000006729
Abstract: To delineate the epileptology, a key part of the SYNGAP1 phenotypic spectrum, in a large patient cohort. Patients were recruited via investigators' practices or social media. We included patients with (likely) pathogenic SYNGAP1 variants or chromosome 6p21.32 microdeletions incorporating SYNGAP1 . We analyzed patients' phenotypes using a standardized epilepsy questionnaire, medical records, EEG, MRI, and seizure videos. We included 57 patients (53% male, median age 8 years) with SYNGAP1 mutations (n = 53) or microdeletions (n = 4). Of the 57 patients, 56 had epilepsy: generalized in 55, with focal seizures in 7 and infantile spasms in 1. Median seizure onset age was 2 years. A novel type of drop attack was identified comprising eyelid myoclonia evolving to a myoclonic-atonic (n = 5) or atonic (n = 8) seizure. Seizure types included eyelid myoclonia with absences (65%), myoclonic seizures (34%), atypical (20%) and typical (18%) absences, and atonic seizures (14%), triggered by eating in 25%. Developmental delay preceded seizure onset in 54 of 56 (96%) patients for whom early developmental history was available. Developmental plateauing or regression occurred with seizures in 56 in the context of a developmental and epileptic encephalopathy (DEE). Fifty-five of 57 patients had intellectual disability, which was moderate to severe in 50. Other common features included behavioral problems (73%) high pain threshold (72%) eating problems, including oral aversion (68%) hypotonia (67%) sleeping problems (62%) autism spectrum disorder (54%) and ataxia or gait abnormalities (51%). SYNGAP1 mutations cause a generalized DEE with a distinctive syndrome combining epilepsy with eyelid myoclonia with absences and myoclonic-atonic seizures, as well as a predilection to seizures triggered by eating.
Publisher: Springer Science and Business Media LLC
Date: 23-06-2022
DOI: 10.1038/S41699-022-00317-5
Abstract: Greater stability of low-dimensional halide perovskites as opposed to their three-dimensional counterparts, alongside their high extinction coefficient and thus excellent emission properties, have made them popular candidates for optoelectronic applications. Topological edges are found in two-dimensional perovskites that show distinct electronic properties. In this work, using Kelvin Probe Force Microscopy, performed on butylammonium lead bromide (BA 2 PbBr 4 ) single crystals with optical bandgap of ~413 nm, we elucidate the electronic response of the edges and their potential impact on photodetector devices. We show that the charge-carriers are accumulated at the edges, increasing with the edge height. Wavelength-dependent surface photovoltage (SPV) measurements reveal that multiple sub-bandgap states exist in BA 2 PbBr 4 . As the edge height increases, the SPV litude at the edges reduces slightly more as compared to the adjacent regions, known as terraces, indicating relatively less reduction in band-bending at the surface due possibly to increased de-population of electrons from sub-bandgap states in the upper bandgap half. The existence of sub-bandgap states is further confirmed by the observation of below-bandgap emission (absorption) peaks characterised by spectral photoluminescence and photothermal deflection spectroscopy measurements. Finally, we fabricated a photodetector using a millimetre size BA 2 PbBr 4 single crystal. Noticeable broadband photodetection response was observed in the sub-bandgap regions under green and red illumination, which is attributed to the existence of sub-bandgap states. Our observations suggest edge-height dependence of charge-carrier behaviour in BA 2 PbBr 4 single crystals, a potential pathway that can be exploited for efficient broadband photodetector fabrication.
Publisher: American Chemical Society (ACS)
Date: 17-06-2022
DOI: 10.1021/JACS.2C04911
Abstract: Creating high surface area nanocatalysts that contain stacking faults is a promising strategy to improve catalytic activity. Stacking faults can tune the reactivity of the active sites, leading to improved catalytic performance. The formation of branched metal nanoparticles with control of the stacking fault density is synthetically challenging. In this work, we demonstrate that varying the branch width by altering the size of the seed that the branch grows off is an effective method to precisely tune the stacking fault density in branched Ni nanoparticles. A high density of stacking faults across the Ni branches was found to lower the energy barrier for Ni
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 2020
Publisher: American Chemical Society (ACS)
Date: 24-10-2019
Abstract: A multilayered nanocomposite designed for biomedical applications based on (TiAlSiY)N/CrN coating implanted by heavy Au
Publisher: American Chemical Society (ACS)
Date: 28-01-2020
DOI: 10.1021/JACS.9B13313
Abstract: Controlling which facets are exposed in nanocrystals is crucial to understanding different activity between ordered and disordered alloy electrocatalysts. We modify the degree of ordering of Pt
Publisher: Elsevier BV
Date: 09-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR03341B
Abstract: Pd–Ru nanoparticles with thin shells and a stable core are shown to improve stability in oxygen evolution reaction catalysis while retaining high activity.
Publisher: IOP Publishing
Date: 15-10-2015
Publisher: American Chemical Society (ACS)
Date: 03-12-2019
Publisher: Wiley
Date: 28-01-2014
Abstract: This paper demonstrates the growth of InGaN nanorods and lateral growth over nanorod arrays using molecular beam epitaxy. It is shown that nitrogen rich growth conditions result in a nanorod array and that, by changing to metal rich conditions, lateral growth may be enhanced to coalesce the nanorods into a continuous overgrown film. Energy dispersive X‐ray spectroscopy has been used to demonstrate that the nanorods display a core‐shell structure with In‐rich cores and In‐poor edges. Transmission Electron Microscopy has shown that the nanorods are free of dislocations. However, when lateral growth occurs basal plane stacking faults are generated. It is shown that this stacking fault generation leads to a change in structure from hexagonal to cubic. When coalescence has occurred large angle grain boundaries are present. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Publisher: Springer Science and Business Media LLC
Date: 13-06-2019
DOI: 10.1038/S41467-019-10621-2
Abstract: Two-dimensional metal oxide pseudocapacitors are promising candidates for size-sensitive applications. However, they exhibit limited energy densities and inferior power densities. Here, we present an electrodeposition technique by which ultrathin CeO 2− x films with controllable volumetric oxygen vacancy concentrations can be produced. This technique offers a layer-by-layer fabrication route for ultrathin CeO 2− x films that render Ce 3+ concentrations as high as ~60 at% and a volumetric capacitance of 1873 F cm −3 , which is among the highest reported to the best of our knowledge. This exceptional behaviour originates from both volumetric oxygen vacancies, which enhance electron conduction, and intercrystallite water, which promotes proton conduction. Consequently, simultaneous charging on the surface and in the bulk occur, leading to the observation of redox pseudocapacitive behaviour in CeO 2− x . Thermodynamic investigations reveal that the energy required for oxygen vacancy formation can be reduced significantly by proton-assisted reactions. This cyclic deposition technique represents an efficient method to fabricate metal oxides of precisely controlled defect concentrations and thicknesses.
Publisher: Wiley
Date: 25-02-2019
DOI: 10.1111/JACE.16358
Publisher: Elsevier BV
Date: 11-2021
Publisher: Springer Science and Business Media LLC
Date: 21-07-2022
DOI: 10.1038/S41560-022-01078-7
Abstract: Understanding carrier loss mechanisms at microscopic regions is imperative for the development of high-performance polycrystalline inorganic thin-film solar cells. Despite the progress achieved for kesterite, a promising environmentally benign and earth-abundant thin-film photovoltaic material, the microscopic carrier loss mechanisms and their impact on device performance remain largely unknown. Herein, we unveil these mechanisms in state-of-the-art Cu 2 ZnSnSe 4 (CZTSe) solar cells using a framework that integrates multiple microscopic and macroscopic characterizations with three-dimensional device simulations. The results indicate the CZTSe films have a relatively long intragrain electron lifetime of 10–30 ns and small recombination losses through bandgap and/or electrostatic potential fluctuations. We identify that the effective minority carrier lifetime of CZTSe is dominated by a large grain boundary recombination velocity (~10 4 cm s −1 ), which is the major limiting factor of present device performance. These findings and the framework can greatly advance the research of kesterite and other emerging photovoltaic materials.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Richard Webster.