A5071780285- Electronic and Structural Properties of Oxides
- TiO2 Photocatalysis and Solar Cells
- Advanced Photocatalysis Techniques
- Catalytic Processes in Materials Science
- Transition Metal Oxide Nanomaterials
- ZnO doping and properties
- Copper-based nanomaterials and applications
- Catalysis and Oxidation Reactions
- Advanced Condensed Matter Physics
- Ga2O3 and related materials
- Topological Materials and Phenomena
- 2D Materials and Applications
- MXene and MAX Phase Materials
- Magnetic and transport properties of perovskites and related materials
- Graphene research and applications
- Gas Sensing Nanomaterials and Sensors
- Advanced Thermoelectric Materials and Devices
- X-ray Spectroscopy and Fluorescence Analysis
- Metal and Thin Film Mechanics
- Ferroelectric and Piezoelectric Materials
- Wireless Power Transfer Systems
- Chalcogenide Semiconductor Thin Films
- Advanced materials and composites
- Magnetic Properties and Synthesis of Ferrites
- Electrocatalysts for Energy Conversion
GNS Science
2019-2025
MacDiarmid Institute for Advanced Materials and Nanotechnology
2015-2024
Advanced Light Source
2018-2024
Victoria University of Wellington
2016-2023
University of Auckland
2013-2021
Lawrence Berkeley National Laboratory
2017-2021
Tuning the photonic band gap (PBG) to electronic (EBG) of Au/TiO2 catalysts resulted in considerable enhancement photocatalytic water splitting hydrogen under direct sunlight. (PBG-357 nm) photocatalyst exhibited superior performance both UV and sunlight compared (PBG-585 are higher than without 3 dimensionally ordered macro-porous structure materials. The very high activity is attributed suppression a fraction electron-hole recombination route due co-incidence PBG with EBG TiO2 These...
Atomic monolayers on semiconductor surfaces represent an emerging class of functional quantum materials in the two-dimensional limit - ranging from superconductors and Mott insulators to ferroelectrics spin Hall insulators. Indenene, a triangular monolayer indium with gap ~ 120 meV is insulator whose micron-scale epitaxial growth SiC(0001) makes it technologically relevant. However, its suitability for room-temperature spintronics challenged by instability topological character air. It...
Transparent thermoelectric materials offer a synergetic performance for energy harvesting as smart windows. Among them, p-type copper iodide (CuI) is preferred due to its low synthesis temperature, moderate conductivity and mobility, high optical transparency. X-ray absorption spectroscopy results showed pre-edge feature in the Cu 2p3/2 spectrum, which suggested presence of Cu0-like defect states γ-CuI films. Interface grain boundaries CuI Cu0 act potential barrier filtering charge carriers,...
We report that oxygen vacancies have a profound impact on phase separation and thermoelectric properties of ITO films grown at room temperature. Oxygen in non-stoichiometric In1.8Sn0.2O2.5 aided the formation In-rich metallic clusters. It yields high electrical conductivity σ = 1540 Scm−1 Seebeck coefficient |α| 27.2 μVK−1, which resulted highest power factor (α2σ 113.8 μW m−1K−2) but low optical transmission (Top ∼ 25%). An increase partial pressure stochiometric In1.8Sn0.2O3 improved...
In this work, ambient pressure x-ray photoelectron spectroscopy (APXPS) is used to study the initial stages of water adsorption on vanadium oxide surfaces. V 2p, O 1s, C and valence band XPS spectra were collected as a function relative humidity in series isotherm isobar experiments. Experiments carried out two VO2 thin films TiO2 (100) substrates, prepared with different surface cleaning procedures. Hydroxyl molecular species identified, up 0.5 ML hydroxide present at minimum humidity,...
X-ray spectroscopy reveals the presence of inter-band gap electronic states e<sub>g</sub>symmetry in M:BiVO<sub>4</sub>(M = Mo, W) PEC anodes.
The efficiency and stability of ${\mathrm{RuO}}_{2}$ in electrocatalysis has made this material a subject intense fundamental industrial interest. surface functionality is rooted its electronic magnetic properties, determined by complex interplay lattice-, spin-rotational, time-reversal symmetries, as well the competition between Coulomb kinetic energies. This was predicted to produce network Dirac nodal lines (DNLs), where valence conduction bands touch along continuous momentum space. Here...
The topological crystalline insulator tin telluride is known to host superconductivity when doped with indium (Sn$_{1-x}$In$_{x}$Te), and for low contents ($x=0.04$) it that the surface states are preserved. Here we present growth, characterization angle resolved photoemission spectroscopy analysis of samples much heavier In doping (up $x\approx0.4$), a regime where superconducting temperature increased nearly fourfold. We demonstrate despite strong p-type doping, Dirac-like persist.
Abstract Synchrotron x-ray spectroscopy was employed to determine the effects of nanostructuring on electronic band structure in V2O5, a promising cathode material and widely used catalyst. V2O5 nanoparticle powders were characterized via P-XRD, TEM, diffuse reflectance UV-Vis-NIR confirm optical bandgap. XES revealed valence O 2p states be upshifted relative bulk, while XAS RIXS showed lowest V 3d conduction static. Together, these changes (in conjunction with an increased density...
The unique electronic band structure of indium nitride InN, part the industrially significant III-N class semiconductors, offers charge transport properties with great application potential due to its robust n-type conductivity. Here, we explore water sensing mechanism InN thin films. Using angle-resolved photoemission spectroscopy, core level and theory, derive carrier density electrical a two-dimensional electron gas, 2DEG, at surface monitor upon in situ modulation adsorbed water. An...
Transparent conducting oxides (TCO) have integral and emerging roles in photovoltaic, thermoelectric energy conversion, more recently, photocatalytic systems. The functional properties of TCOs, thus their role these applications, are often mediated by the bulk electronic band structure but also strongly influenced native surface 2D electron gas (2DEG), particularly under operating conditions. This study investigates 2DEG, its response to changes chemistry, at (111) model TCO In2 O3 , through...
Abstract Molybdenum carbides are promising low‐cost electrocatalysts for electrolyzers, fuel cells, and batteries. However, synthesis of ultrafine, phase‐pure carbide nanoparticles ( diameter < 5 nm) with large surface areas remains challenging due to uncontrollable agglomeration that occurs during traditional high temperature syntheses. This work presents a scalable, physical approach synthesize molybdenum at room by ion implantation. By tuning the implantation conditions, various...
${\text{LiCu}}_{3}{\mathrm{O}}_{3}$ is an antiferromagnetic mixed valence cuprate where trilayers of edge-sharing Cu(II)O ($3{d}^{9}$) are sandwiched in between planes Cu(I) ($3{d}^{10}$) ions, with Li stochastically substituting Cu(II). Angle-resolved photoemission spectroscopy (ARPES) and density functional theory reveal two insulating electronic subsystems that segregated spite sharing common oxygen atoms: a Cu ${d}_{{z}^{2}}/\mathrm{O}$ ${p}_{z}$ derived band (VB) dispersing on the...
This paper compares the photocatalytic activities of Au/TiO 2 (Au loadings 0–4 wt.%) and Ag/TiO photocatalysts (Ag for H production from ethanol-water mixtures under UV irradiation. Au Ag nanoparticles were deposited on commercially available Degussa P25 TiO (85% anatase, 15% rutile) using deposition-precipitation liquid impregnation methods, respectively. TEM analyses showed average noble metal nanoparticle size to be ~5 nm ~3 photocatalysts. a strong localised surface plasmon resonance...
Polarization dependent V L-edge XAS spectra showing anisotropy in the electronic band structure of a W:BiVO<sub>4</sub> single crystal.
Emergent order at mesoscopic length scales in condensed matter can provide fundamental insight into the underlying competing interactions and their relationship with parameter. Using spectromicroscopy, we show that stripe near metal-insulator transition (MIT) of strained ${\mathrm{VO}}_{2}$ represents periodic modulations both crystal symmetry V---V dimerization. Above MIT, unexpectedly find long-range dimer strength become dissociated beyond $\ensuremath{\approx}200\text{ }\text{...
The active (110) surface of the benchmark oxygen evolution catalyst RuO2 spans a flat-band state (FBSS) between projections its Dirac nodal lines (DNLs) that define electronic properties this functional semimetal. Monitoring well-known adsorption processes H2, O2, NO, and CO by in operando angle-resolved photoemission spectroscopy, we selectively modify oxidation individual Ru sites identify nature FBSS: stabilized bridging Obr pz, FBSS disperses along ⟨001⟩ oriented chains Rubr 4dz2...