ORCID Profile
0000-0002-8382-1714
Current Organisation
University of Adelaide
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Publisher: Elsevier BV
Date: 1995
Publisher: Springer Science and Business Media LLC
Date: 10-2005
Publisher: John Wiley & Sons, Inc.
Date: 11-04-2014
Publisher: IEEE
Date: 2005
Publisher: American Chemical Society (ACS)
Date: 30-08-2022
Publisher: Wiley
Date: 07-2021
Abstract: Recently, the creation of new heterogeneous catalysts using the unique electronic/geometric structures of small metal nanoclusters (NCs) has received considerable attention. However, to achieve this, it is extremely important to establish methods to remove the ligands from ligand‐protected metal NCs while preventing the aggregation of metal NCs. In this study, the ligand‐desorption process during calcination was followed for metal‐oxide‐supported 2‐phenylethanethiolate‐protected gold (Au) 25‐atom metal NCs using five experimental techniques. The results clearly demonstrate that the ligand‐desorption process consists of ligand dissociation on the surface of the metal NCs, adsorption of the generated compounds on the support and desorption of the compounds from the support, and the temperatures at which these processes occurred were elucidated. Based on the obtained knowledge, we established a method to form a metal‐oxide layer on the surface of Au NCs while preventing their aggregation, thereby succeeding in creating a water‐splitting photocatalyst with high activity and stability.
Publisher: American Chemical Society (ACS)
Date: 18-07-2022
DOI: 10.26434/CHEMRXIV-2022-LLT2Q
Abstract: The synthesis of kinetically-stabilized, i.e., metastable, dielectric semiconductors, represents a major frontier within key technologically-important fields as compared to thermodynamically-stable solids that have received considerably more attention. Of longstanding theoretical interest are Sn(II) perovskites (e.g., Sn(Zr1/2Ti1/2)O3, SZT), which are Pb-free analogues of (Pb(Zr1/2Ti1/2)O3, PZT), a commercial piezoelectric composition that is dominant in the electronics industry. Herein, we describe the synthesis of this metastable SZT dielectric through a low-temperature flux reaction technique. The SZT has been found, for the first time, to grow and to be stabilized as a nanoshell at the surfaces of Ba(Zr1/2Ti1/2)O3 (BZT) particles, i.e., forming as BZT-SZT core-shell particles, as a result of Sn(II) cation exchange. In situ powder X-ray diffraction (XRD) and transmission electron microscopy data show that the SZT nanoshells result from the controlled cation diffusion of Sn(II) cations into the BZT particles, with tunable thicknesses of ~25 nm to 100 nm. The SZT nanoshell is calculated to possess a metastability of ~ 0.5 eV atom–1 with respect to decomposition to SnO, ZrO2, and TiO2, and thus cannot currently be prepared as stand-alone particles. Rietveld refinements of the XRD data are consistent with a two-phase BZT-SZT model, with each phase possessing a generally cubic perovskite-type structure and nearly identical lattice parameters. Mössbauer spectroscopic data (119Sn) are consistent with Sn(II) cations within the SZT nanoshells and an outer ~5 to 10 nm surface region comprised of oxidized Sn(IV) cations from exposure to air and water. The optical band gap of the SZT shell was found to be ~2.2 eV, which is redshifted by ~1.2 eV as compared to BZT. This closing of the band gap was probed by X-ray photoelectron spectroscopy and found to stem from a shift of the valence band edge to higher energies (~1.07 eV) as a result of the addition of the Sn 5s2 orbitals forming a new higher-energy valence band. In summary, a novel synthetic tactic is demonstrated to be effective in preparing highly metastable SZT and representing a generally useful strategy for the kinetic stabilization of other predicted, metastable dielectrics.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NR04202E
Abstract: This work established a simple method for the size-selective synthesis of a series of ligand-protected platinum nanoclusters with superior oxygen reduction reactivity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1MA01226F
Abstract: Chromium hydroxide overlayer have been shown to have great potential to protects the phosphine-ligated Au clusters from agglomeration after the removal of the ligands and under conditions of photocatalytic water splitting.
Publisher: American Chemical Society (ACS)
Date: 05-04-2003
DOI: 10.1021/JO0204505
Abstract: Twist-twist pi-conjugated (TTPC) pi systems promise unique properties with their 90 degrees twist angles. Di-sec-alkyl substituted stilbenes, 5, were prepared by low-valent titanium coupling of phenyl ketones, 4. Long alkyl chains stopped the coupling reaction. Stilbenes 5 were shown to be approximately 90% TTPC. Inserting TTPC units into poly(p-phenylene) polymers created highly fluorescent, soluble, TTPC pi systems with weak electronic segmentation for organic light emitting diode (OLED) studies.
No related grants have been discovered for D J Osborn III.