ORCID Profile
0000-0002-7251-126X
Current Organisation
The University of Newcastle
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Publisher: American Chemical Society (ACS)
Date: 24-05-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CC02178C
Abstract: The rational, deliberate design of supramolecular architectures is of great importance for the discovery of complex materials.
Publisher: AIP Publishing
Date: 11-12-2020
DOI: 10.1063/5.0027080
Abstract: We report a systematic investigation of in idual and multisite Hubbard-U corrections for the electronic, structural, and optical properties of the metal titanate oxide d0 photocatalysts SrTiO3 and rutile/anatase TiO2. Accurate bandgaps for these materials can be reproduced with local density approximation and generalized gradient approximation exchange-correlation density functionals via a continuous series of empirically derived Ud and Up combinations, which are relatively insensitive to the choice of functional. On the other hand, lattice parameters are much more sensitive to the choice of Ud and Up, but in a systematic way that enables the Ud and Up corrections to be used to qualitatively gauge the extent of self-interaction error in the electron density. Modest Ud corrections (e.g., 4 eV–5 eV) yield the most reliable dielectric response functions for SrTiO3 and are comparable to the range of Ud values derived via linear response approaches. For r-TiO2 and a-TiO2, however, the Ud,p corrections that yield accurate bandgaps fail to accurately describe both the parallel and perpendicular components of the dielectric response function. Analysis of in idual Ud and Up corrections on the optical properties of SrTiO3 suggests that the most consequential of the two in idual corrections is Ud, as it predominately determines the accuracy of the dominant excitation from O-2p to the Ti-3d t2g/eg orbitals. Up, on the other hand, can be used to shift the entire optical response uniformly to higher frequencies. These results will assist high-throughput and machine learning approaches to screening photoactive materials based on d0 photocatalysts.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/CH16673
Abstract: The co-crystallisation behaviour of three symmetrical dipyridylacetylacetone ligands (1,3-di(2-pyridyl)-1,3-propanedione (o-bppdH), 1,3-di(3-pyridyl)-1,3-propanedione (m-bppdH), and 1,3-di(4-pyridyl)-1,3-propanedione (p-bppdH)), with the linear halogen-bond donor 1,4-diiodotetrafluorobenzene (1,4-DITFB) has been investigated. The reaction of these components under ambient conditions in a 1 : 1 stoichiometry produced four halogen-bonded assemblies ([o-bppdH·1,4-DITFB, [m-bppdH·1,4-DITFB], [2(m-bppdH)·1,4-DITFB], and [p-bppdH·1,4-DITFB]). The combination of multiple supramolecular interactions including halogen bonding, hydrogen bonding, and π-stacking produces a range of supramolecular architectures, including one-, two-, and three-dimensional motifs. The crystal structure of m-bppdH is also reported.
Publisher: American Chemical Society (ACS)
Date: 10-04-2019
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.JINORGBIO.2016.02.008
Abstract: di-Zinc(II) complexes of the ligands 2,6-bis((bis(2-methoxyethyl)amino)methyl)-4-methylphenol (HL1), 2,6-bis(bis(hydroxyethyl)aminomethyl)-4-methylphenol (HL2) and 2,6-bis((hydroxyethyl)(methoxyethyl)-aminomethyl)-4-methylphenol (HL3) have been prepared and characterized. The three ligands differ in their donor types, having ether donors (HL1), alkoxido donors (HL2) and both ether and alkoxido donors (HL3). These differences allowed an investigation into the role of the potential nucleophiles in the hydrolysis reaction with the phosphodiester substrate bis(2,4-dinitrophenyl)phosphate (BDNPP). In addition, the di-Mg(II) complex of ligand HL2 was prepared in order to examine the potential for Mg(II) to replace Zn(II) in these biomimetic systems. Kinetically relevant pK
Publisher: Wiley
Date: 26-09-2016
Abstract: An asymmetric 'Pacman' metalloligand, [Zn(PXT)], which features a cofacial Zn
Publisher: AIP Publishing
Date: 26-03-2021
DOI: 10.1063/5.0045526
Abstract: We investigate how the Hubbard U correction influences vacancy defect migration barriers in transition metal oxide semiconductors. We show that, depending on the occupation of the transition metal d orbitals, the Hubbard U correction can cause severe instabilities in the migration barrier energies predicted using generalized gradient approximation density functional theory (GGA DFT). For the d0 oxide SrTiO3, applying a Hubbard correction to the Ti4+ 3d orbitals below 4–5 eV yields a migration barrier of ∼0.4 eV. However, above this threshold, the barrier increases suddenly to ∼2 eV. This sudden increase in the transition state barrier arises from the Hubbard U correction changing the Ti4+ t2g/eg orbital occupation, and hence electron density localization, along the migration pathway. Similar results are observed in the d10 oxide ZnO however, significantly larger Hubbard U corrections must be applied to the Zn2+ 3d orbitals for the same instability to be observed. These results highlight important limitations to the application of the Hubbard U correction when modeling reactive pathways in solid state materials using GGA DFT.
Publisher: Wiley
Date: 06-02-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TA02280E
Abstract: First principles calculations reveal charge-dependent vacancy diffusion mechanisms in mixed anion photocatalytic materials.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1MA00122A
Abstract: First-principles calculations predict the stability and mobility of vacancy defects in niobium perovskite oxynitrides, aiding defect engineering for enhanced photocatalysis.
Publisher: Wiley
Date: 08-05-2023
DOI: 10.1002/WENE.476
Abstract: Water splitting (WS) driven by solar energy is considered as a promising strategy to produce renewable hydrogen from water with minimal environmental impact. Realization of large‐scale hydrogen production by this approach requires cost‐effective, efficient and stable materials to drive the WS reaction. Perovskite oxides have recently attracted widespread attention in WS applications due to their unique structural features, such as compositional and structural flexibility allowing them to achieve desired sunlight absorption capability, precise control of electrocatalytic and redox activity to drive the chemical reaction, tuneable bandgaps and band edges, and earth‐abundance. However, perovskite oxides contain a large family of metal oxides and experimental exploration of novel perovskites without a priori knowledge of their properties could be costly and time‐consuming. First‐principles approaches such as density functional theory (DFT) are a useful and cost‐effective alternative towards this end. In this review, DFT‐based calculations for accurate prediction of the critical properties of ABO 3 perovskite oxides relevant to WS processes are surveyed. Structural, electronic, optical, surface, and thermal properties are grouped according to their relevance to photocatalytic (PC), electrochemical (EC), photo‐electrochemical (PEC), and solar thermal water splitting (STWS) processes. The challenges associated with the choice of exchange‐correlation (XC) functional in DFT methods for precise prediction of these properties are discussed and specific XC functionals have been recommended where experimental comparisons are possible. This article is categorized under: Sustainable Energy Solar Energy Emerging Technologies Hydrogen and Fuel Cells Emerging Technologies Materials
No related grants have been discovered for Joshua J Brown.