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Articles 1 - 21 of 21
Full-Text Articles in Physical Sciences and Mathematics
Dye Regeneration And Charge Recombination In Dye-Sensitized Solar Cells With Ferrocene Derivatives As Redox Mediators, Torben Daeneke, Attila J. Mozer, Tae-Hyuk Kwon, Noel W. Duffy, Andrew B. Holmes, Udo Bach, Leone Spiccia
Dye Regeneration And Charge Recombination In Dye-Sensitized Solar Cells With Ferrocene Derivatives As Redox Mediators, Torben Daeneke, Attila J. Mozer, Tae-Hyuk Kwon, Noel W. Duffy, Andrew B. Holmes, Udo Bach, Leone Spiccia
Faculty of Science - Papers (Archive)
Ferrocene compounds are promising redox shuttles for application in dye-sensitized solar cells (DSCs). Chemical modification of the cyclopentadienyl rings is easily achievable affording almost unlimited variation of the redox properties. This allows fine-tuning of the driving force for dye-regeneration and optimization of the energy conversion efficiency of DSCs. Herein, six ferrocene derivatives have been chosen for investigation which cover the large redox potential range of 0.85 V, by virtue of simple alkylation and halogenation of the cyclopentadienyl ring, and enable improved matching of the energy levels of the sensitizer and the electrolyte. Although the focus of this work was to …
Sustained Solar Hydrogen Generation Using A Dye-Sensitised Nio Photocathode/Bivo4 Tandem Photo-Electrochemical Device, Lei Tong, Akihide Iwase, Andrew Nattestad, Udo Bach, Martin Weidelener, Gunther Gotz, Amaresh Mishra, Peter Bauerle, Rose Amal, Gordon G. Wallace, Attila J. Mozer
Sustained Solar Hydrogen Generation Using A Dye-Sensitised Nio Photocathode/Bivo4 Tandem Photo-Electrochemical Device, Lei Tong, Akihide Iwase, Andrew Nattestad, Udo Bach, Martin Weidelener, Gunther Gotz, Amaresh Mishra, Peter Bauerle, Rose Amal, Gordon G. Wallace, Attila J. Mozer
Faculty of Science - Papers (Archive)
Solar hydrogen generation sustained for at least several hours is demonstrated using a dye-sensitised nickel(II) oxide photocathode and BiVO4 photoanode connected in a tandem configuration. H2 evolution rate is 120 nmol h−1 (>80% faradaic efficiency) without electrical bias or sacrificial oxidant/reductant, at pH = 7 using visible light (>420 nm).
Remote Sensing Of Co2 And Ch4 Using Solar Absorption Spectrometry With A Low Resolution Spectrometer, C Petri, T Warneke, N Jones, T Ridder, J Messerschmidt, T Weinzierl, M Geibel, J Notholt
Remote Sensing Of Co2 And Ch4 Using Solar Absorption Spectrometry With A Low Resolution Spectrometer, C Petri, T Warneke, N Jones, T Ridder, J Messerschmidt, T Weinzierl, M Geibel, J Notholt
Faculty of Science - Papers (Archive)
Throughout the last few years solar absorption Fourier Transform Spectrometry (FTS) has been further developed to measure the total columns of CO2 and CH4. The observations are performed at high spectral resolution, typically at 0.02 cm(-1). The precision currently achieved is generally better than 0.25%. However, these high resolution instruments are quite large and need a dedicated room or container for installation. We performed these observations using a smaller commercial interferometer at its maximum possible resolution of 0.11 cm(-1). The measurements have been performed at Bremen and have been compared to observations using our high resolution instrument also situated at …
Remote Sensing Of Atmospheric Trace Gases By Ground-Based Solar Fourier Transform Infrared Spectroscopy, Clare Paton-Walsh
Remote Sensing Of Atmospheric Trace Gases By Ground-Based Solar Fourier Transform Infrared Spectroscopy, Clare Paton-Walsh
Faculty of Science - Papers (Archive)
The changing composition of the earth’s atmosphere is a matter of intense scientific research as we strive to understand details of the physical and chemical mechanisms that control our climate. Fourier transform spectroscopy has been applied very successfully to the study of trace gases in the atmosphere by examining terrestrial atmospheric absorption lines in the infrared spectrum from the Sun. In fact many gases were first discovered in the atmosphere during the 1940’s from their absorption features in the infrared solar spectrum. These early optical absorption measurements of the atmosphere using the Sun as a source were made with grating …
Evidence Of Solar And Tropical-Ocean Forcing Of Hydroclimate Cycles In Southeastern Australia For The Past 6500 Years, Hamish A. Mcgowan, Samuel K. Marx, Joshua Soderholm, John Denholm
Evidence Of Solar And Tropical-Ocean Forcing Of Hydroclimate Cycles In Southeastern Australia For The Past 6500 Years, Hamish A. Mcgowan, Samuel K. Marx, Joshua Soderholm, John Denholm
Faculty of Science - Papers (Archive)
Evidence of solar and tropical‐ocean forcing of climate cycles has been found in numerous palaeoclimate records. Numerical modelling studies show physical mechanisms by which direct and indirect solar forcing may affect climate, while there is mounting evidence of solar forcing of tropical ocean‐atmosphere teleconnections. This study has developed a 6500 year record of dust deposition, a proxy for regional hydroclimate variability for the Snowy Mountains region of Australia. Spectral analysis of the record provides evidence of statistically significant cycles in dust deposition of 35–43 years, 62–73 years, 161 years and 2200 years. These correlate with variability in solar irradiance and …
Flexible And Compressible Goretex-Pedot Membrane Electrodes For Solid-State Dye-Sensitized Solar Cells, Attila J. Mozer, Dillip K. Panda, Sanjeev Gambhir, Anthony C. Romeo, Bjorn Winther-Jensen, Gordon G. Wallace
Flexible And Compressible Goretex-Pedot Membrane Electrodes For Solid-State Dye-Sensitized Solar Cells, Attila J. Mozer, Dillip K. Panda, Sanjeev Gambhir, Anthony C. Romeo, Bjorn Winther-Jensen, Gordon G. Wallace
Faculty of Science - Papers (Archive)
A porous, flexible electrode based on a PTFE (Teflon) membrane (Goretex) coated with a metallic current collector and a conducting polymer (poly(3,4-ethylenedioxythiophene), PEDOT) has been developed for applications in solidstate dye-sensitized solar cells. Its low sheet resistance and compressibility make it an ideal electrode on uneven TiO2 surfaces with high efficiency and reproducibility. The porous nature of the electrode enables the feed-through of reactants and treatment agents, which opens up exciting opportunities to interface these photoelectrochemical devices with electrocatalytic, energy conversion, and storage systems. Postfabrication bonding of the photoanode and the Goretex-Au-PEDOT electrode is demonstrated.
Ionic Liquid Electrolyte Porphyrin Dye Sensitised Solar Cells, Vanessa Armel, Jennifer Pringle, Maria Forsyth, Douglas Macfarlane, David L. Officer, Pawel W. Wagner
Ionic Liquid Electrolyte Porphyrin Dye Sensitised Solar Cells, Vanessa Armel, Jennifer Pringle, Maria Forsyth, Douglas Macfarlane, David L. Officer, Pawel W. Wagner
Faculty of Science - Papers (Archive)
Ionic liquid electrolytes based on a number of imidazolium, quaternary ammonium and phosphonium cations have been developed for porphyrin dye sensitised solar cells yielding efficiencies of up to 5.2% at 0.68 Sun.
Microsecond Dye Regeneration Kinetics In Efficient Solid State Dye-Sensitized Solar Cells Using A Photoelectrochemically Deposited Pedot Hole Conductor, Attila J. Mozer, Dillip K. Panda, Sanjeev Gambhir, B. Winther-Jensen, Gordon G. Wallace
Microsecond Dye Regeneration Kinetics In Efficient Solid State Dye-Sensitized Solar Cells Using A Photoelectrochemically Deposited Pedot Hole Conductor, Attila J. Mozer, Dillip K. Panda, Sanjeev Gambhir, B. Winther-Jensen, Gordon G. Wallace
Faculty of Science - Papers (Archive)
Microsecond dye-regeneration kinetics was observed in efficient solid state dye-sensitized solar cells using photoelectrochemically deposited poly(3,4-ethylenedioxythiophene (PEDOT) hole conductors using transient absorption spectroscopy. The dye-regeneration rate is orders of magnitude slower than the case using the I-/I3- redox couple or commonly used small molecule hole conductor and is attributed to the low dye to PEDOT ratio within the films.
Catalytic Solar Water Splitting Inspired By Photosynthesis. Homogeneous Catalysts With A Mechanical ("Machine-Like") Action, Gerhard F. Swiegers, G Charles Dismukes, Leone Spiccia, Robin Brimblecombe, Annette Koo, Jun Chen, Gordon G. Wallace
Catalytic Solar Water Splitting Inspired By Photosynthesis. Homogeneous Catalysts With A Mechanical ("Machine-Like") Action, Gerhard F. Swiegers, G Charles Dismukes, Leone Spiccia, Robin Brimblecombe, Annette Koo, Jun Chen, Gordon G. Wallace
Faculty of Science - Papers (Archive)
Chemical reactions may be controlled by either: the minimum threshold energy that must be overcome during collisions between reactant molecules / atoms (the Activation Energy, Ea), or: the rate at which reactant collisions occur (the Collision Frequency, A) (for reactions with low Ea). Reactions of type (2) are governed by the physical, mechanical interaction of the reactants. Such mechanical processes are unusual, but not unknown in molecular catalysts. We examine the catalytic action and macroscopic properties of several abiological mechanical catalysts and show that they display distinct similarities to enzymes in general. An abiological model of the Photosystem II Water …
Improved Performance Of Porphyrin-Based Dye Sensitised Solar Cells By Phosphinic Acid Surface Treatment, K Sunahara, Alessandra Allegrucci, S Mori, Naomi A. Lewcenko, Leone Spiccia, Attila J. Mozer, Lynn Dennany, Pawel W. Wagner, David L. Officer
Improved Performance Of Porphyrin-Based Dye Sensitised Solar Cells By Phosphinic Acid Surface Treatment, K Sunahara, Alessandra Allegrucci, S Mori, Naomi A. Lewcenko, Leone Spiccia, Attila J. Mozer, Lynn Dennany, Pawel W. Wagner, David L. Officer
Faculty of Science - Papers (Archive)
Chemical surface treatment of porphyrin-sensitised titania films using bis-(4-methoxyphenyl)phosphinic acid after dye adsorption, results in large improvements in DSSC efficiencies which originate primarily from higher short circuit currents. The result was attributed to a positive shift in the TiO2 quasi-Fermi level with simultaneous retardation of charge recombination. High device performances have been achieved even using simplified electrolyte matrices devoid of the common additives, LiI and t-butylpyridine.
A Spectroscopic And Dft Study Of Thiophene-Substituted Metalloporphyrins As Dye-Sensitized Solar Cell Dyes, Sanjeev Gambhir, Keith C. Gordon, David L. Officer, Samual J. Lind
A Spectroscopic And Dft Study Of Thiophene-Substituted Metalloporphyrins As Dye-Sensitized Solar Cell Dyes, Sanjeev Gambhir, Keith C. Gordon, David L. Officer, Samual J. Lind
Faculty of Science - Papers (Archive)
A combination of density functional theory calculations, electronic absorption and resonance Raman spectroscopy has been applied to a series of beta-substituted zinc porphyrins to elucidate how the substituent affects the electronic structure of the metalloporphyrin and assign the nature of electronic transitions in the visible region. The use of conjugated beta substituents invokes a large perturbation to both the nature and energy of the frontier molecular orbitals and results in the generation of additional molecular orbitals from the parent metalloporphyrin species. A complicated electronic absorption spectra is observed which can be rationalised by an extension of Goutermans' four-orbital model. The …
Long-Term Tropospheric Formaldehyde Concentrations Deduced From Ground-Based Fourier Transform Solar Infrared Measurements, N B. Jones, K Riedel, W Allan, S Wood, P I. Palmer, K Chance, J Notholt
Long-Term Tropospheric Formaldehyde Concentrations Deduced From Ground-Based Fourier Transform Solar Infrared Measurements, N B. Jones, K Riedel, W Allan, S Wood, P I. Palmer, K Chance, J Notholt
Faculty of Science - Papers (Archive)
We report a 13-year (1992–2005) dataset of total column measurements of formaldehyde (HCHO) over Lauder, New Zealand, inferred from solar infrared spectra measured using a high-resolution Fourier Transform Spectrometer (FTS). Ambient HCHO concentrations at this rural location are often close to levels typical of remote marine environments (<250 ppt), which are close to the detection limit using standard techniques. Consequently we develop a new method that successfully produces HCHO columns with sufficient sensitivity throughout the whole season. HCHO columns over Lauder have a strong seasonal cycle (±50%), with a mean column of 4.9×1015 molecules cm−2, peaking during summer months. A simple box model of CH4 oxidation reproduces the observed broad-scale seasonal cycle, but significantly underestimates the seasonal peak HCHO ground concentrations during summer. This suggests the existence of an additional significant source of HCHO, possibly isoprene that cannot be explained by oxidation of CH4 alone. The ground-based FTS column data compare well with collocated HCHO column measurements from the Global Ozone Monitoring Experiment (GOME) satellite instrument during the operational period of GOME (1996–2001, r2=0.65, mean bias=10%, n=48).
Enhanced Performance Of Dye Sensitized Solar Cells Utilizing Platinum Electrodeposit Counter Electrodes, Attila J. Mozer, George Tsekouras, Gordon G. Wallace
Enhanced Performance Of Dye Sensitized Solar Cells Utilizing Platinum Electrodeposit Counter Electrodes, Attila J. Mozer, George Tsekouras, Gordon G. Wallace
Faculty of Science - Papers (Archive)
Enhanced performance was observed for dye-sensitized solar cells (DSSCs) utilizing counter electrodes based on Pt electrodeposits compared to counter electrodes based on sputtered Pt. Scanning electron microscopy of Pt electrodeposits revealed that the use of an initial cathodic overpotential pulse followed by steady electrodeposition at a mild cathodic potential yielded ∼40nm particles, compared to ∼600nm particles when no such pulse was used. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) of electrode materials suggested that Pt electrodeposits would give enhanced performance as DSSC counter electrodes compared to sputtered Pt, and this was confirmed by device testing. EIS characterization of DSSCs under …
Long-Term Tropospheric Formaldehyde Concentrations Deduced From Ground-Based Fourier Transform Solar Infrared Measurements, Nicholas B. Jones, K Riedel, Barbara M. Allen, S. W. Wood, Paul Palmer, K Chance, Justus Notholt
Long-Term Tropospheric Formaldehyde Concentrations Deduced From Ground-Based Fourier Transform Solar Infrared Measurements, Nicholas B. Jones, K Riedel, Barbara M. Allen, S. W. Wood, Paul Palmer, K Chance, Justus Notholt
Faculty of Science - Papers (Archive)
We report a 13-year (1992–2005) dataset of total column measurements of formaldehyde (HCHO) over Lauder, New Zealand, inferred from solar infrared spectra measured using a high-resolution Fourier Transform Spectrometer (FTS). Ambient HCHO concentrations at this rural location are often close to levels typical of remote marine environments (<250 ppt), which are close to the detection limit using standard techniques. Consequently we develop a new method that successfully produces HCHO columns with sufficient sensitivity throughout the whole season. HCHO columns over Lauder have a strong seasonal cycle (±50%), with a mean column of 4.9×1015 molecules cm−2, peaking during summer months. A simple box model of CH4 oxidation reproduces the observed broad-scale seasonal cycle, but significantly underestimates the seasonal peak HCHO ground concentrations during summer. This suggests the existence of an additional significant source of HCHO, possibly isoprene that cannot be explained by oxidation of CH4 alone. The ground-based FTS column data compare well with collocated HCHO column measurements from the Global Ozone Monitoring Experiment (GOME) satellite instrument during the operational period of GOME (1996–2001, r2=0.65, mean bias=10%, n=48).
Ground-Based Solar Absorption Ftir Spectroscopy: Characterization Of Retrievals And First Results From A Novel Optical Design Instrument At A New Ndacc Complementary Station, Aldona Waiacek, J R. Taylor, K Strong, R Saari, T Kertzenmacher, Nicholas B. Jones, David W. Griffith
Ground-Based Solar Absorption Ftir Spectroscopy: Characterization Of Retrievals And First Results From A Novel Optical Design Instrument At A New Ndacc Complementary Station, Aldona Waiacek, J R. Taylor, K Strong, R Saari, T Kertzenmacher, Nicholas B. Jones, David W. Griffith
Faculty of Science - Papers (Archive)
The authors describe the optical design of a high-resolution Fourier Transform Spectrometer (FTS), which serves as the primary instrument at the University of Toronto Atmospheric Observatory (TAO). The FTS is dedicated to ground-based infrared solar absorption atmospheric measurements from Toronto, Ontario, Canada. Instrument performance is discussed in terms of instrumental line shape (ILS) and phase error and modulation efficiency as a function of optical path difference. Typical measurement parameters are presented together with retrieval parameters used to derive total and partial column concentrations of ozone. Retrievals at TAO employ the optimal estimation method (OEM), and some impacts of the necessary …
First Detection Of Meso-Thermospheric Nitric Oxide (No) By Ground-Based Ftir Solar Absorption Spectroscopy, Aldona Wiacek, Nicholas B. Jones, K Strong, J R. Taylor, Richard L. Mittermeier, Hans Fast
First Detection Of Meso-Thermospheric Nitric Oxide (No) By Ground-Based Ftir Solar Absorption Spectroscopy, Aldona Wiacek, Nicholas B. Jones, K Strong, J R. Taylor, Richard L. Mittermeier, Hans Fast
Faculty of Science - Papers (Archive)
We report the first detection of mesospheric-lower thermospheric (MLT, 50–130 km) NO from ground-based FTIR solar absorption spectra using Lorentz- and Doppler-broadened solar absorption lines in the stratosphere and in the MLT, respectively. We present the first characterization of vertical sensitivity in the FTIR NO retrieval and show that MLT NO partial columns can be retrieved with ~1 independent piece of information using a climatological NO profile extending up to 130 km. The information content analysis also improves the characterization of stratospheric partial column retrievals and is relevant to NO results obtained at other Network for the Detection of Stratospheric …
Atmospheric Carbonyl Sulfide (Ocs) Variation From 1992-2004 By Ground-Based Solar Ftir Spectrometry, Nicholas M. Deutscher, Nicholas B. Jones, David W. Griffith, S. W. Wood, F Murcray
Atmospheric Carbonyl Sulfide (Ocs) Variation From 1992-2004 By Ground-Based Solar Ftir Spectrometry, Nicholas M. Deutscher, Nicholas B. Jones, David W. Griffith, S. W. Wood, F Murcray
Faculty of Science - Papers (Archive)
Analysis of ground-based high-resolution solar FTIR absorption spectra from four sites was performed to determine trends and variability in OCS columns over the period 1992–2004. The sites were Wollongong, Australia (34.45° S, 150.88° E), Lauder, New Zealand (45.0° S, 169.7° E), Arrival Heights, Antarctica (77.8° S, 166.6° E) and Mauna Loa, Hawaii (19.5° N, 155.6° W). Small but significant long-term trends of −0.18±0.02% yr-1 above Hawaii, −0.30±0.12% yr-1 above Wollongong and −0.29±0.14% yr-1 above Lauder, were seen. No significant trend was seen above Arrival Heights. A large peak-to-peak seasonal difference observed in 1996–1997 above Wollongong and reported …
Seasonal Variations Of Co And Hcn In The Troposphere Measured By Solar Absorption Spectroscopy Over Poker Flat, Alaska, Y Kasai, A. Kagawa, Nicholas B. Jones, A. Fujiwara, K. Seki, Y. Murayama, F Murcray
Seasonal Variations Of Co And Hcn In The Troposphere Measured By Solar Absorption Spectroscopy Over Poker Flat, Alaska, Y Kasai, A. Kagawa, Nicholas B. Jones, A. Fujiwara, K. Seki, Y. Murayama, F Murcray
Faculty of Science - Papers (Archive)
Tropospheric partial column abundances of CO and HCN have been retrieved from infrared solar spectra observed with a ground-based spectrometer at Poker Flat Alaska (65°N, 147°W) over the time period from 2000 to 2004. From these data we report the transpacific transport induced inter-annual variability of tropospheric CO over Poker Flat. This is the first report of solar infrared data from the Poker Flat station, where the geographical location of the site means that remote sensing measurements are sampling the transport of transpacific air parcels going to Northern America from Eastern Siberia and Asia. The five year time-span of the …
Palaeovolcanic Forcing Of Short-Term Dendroisotopic Depletion: The Effect Of Decreased Solar Intensity On Irish Oak, N. Ogle, Christian Turney, R.M. Kalin, L. O'Donnell, C.J. Butler
Palaeovolcanic Forcing Of Short-Term Dendroisotopic Depletion: The Effect Of Decreased Solar Intensity On Irish Oak, N. Ogle, Christian Turney, R.M. Kalin, L. O'Donnell, C.J. Butler
Faculty of Science - Papers (Archive)
The climatic effects of historical volcanic eruptions are well documented in the literature. What are less certain however, are the effects of eruptions on more distant environments, particularly vegetation. Here we present sub-annual δ13C records from two high-resolution Irish oak (Quercus spp.) chronologies that span the Laki (Grímsvötn) 1783–84 and Tambora 1815 eruptions. In both instances, a significant depletion in δ13C is recorded within the trees following the eruption (∼1.8‰). Historical meteorological datasets from observatories near to the trees sampled demonstrate that the shifts in carbon isotopic content cannot be accounted for by changes in …
Combined Effects Of Solar Radiation And Desiccation On The Mortality And Development Of Encapsulated Embryos Of Rocky Shore Gastropods, R. Przeslawski
Combined Effects Of Solar Radiation And Desiccation On The Mortality And Development Of Encapsulated Embryos Of Rocky Shore Gastropods, R. Przeslawski
Faculty of Science - Papers (Archive)
Intertidal encapsulated embryos may be synchronously exposed to many environmental stressors, but interactions between some of these factors remain poorly understood. Here, the effects of solar radiation and desiccation on embryonic mortality and developmental rates were assessed using laboratory and field experiments. Egg masses of 3 intertidal gastropod species were exposed for 72 h to combinations of spectral (full spectrum, UV-blocked, dark) and daily emersion treatments (control, 15, 30, 60 min). Siphonaria denticulata and Bembicium nanum embryos were expected to be tolerant to emersion and UVR as they are routinely deposited on exposed rock platforms. In contrast, Dolabrifera brazieri embryos …
Shipborne Solar Absorption Measurements Of Co2, Ch4, N2o And Co And Comparison With Sciamachy Wfm-Doas Retrievals, T Warneke, R De Beek, M Buchwitz, J Notholt, A Schulz, Voltaire A. Velazco, O Schrems
Shipborne Solar Absorption Measurements Of Co2, Ch4, N2o And Co And Comparison With Sciamachy Wfm-Doas Retrievals, T Warneke, R De Beek, M Buchwitz, J Notholt, A Schulz, Voltaire A. Velazco, O Schrems
Faculty of Science - Papers (Archive)
CO, CH4, N2O and CO2 were retrieved from high resolution solar absorption spectra obtained during a ship cruise from Capetown to Bremerhaven in January/February 2003 by Fourier Transform Infrared (FTIR) spectroscopy. Precisions of better than 0.5% for the column averaged volume mixing ratios (VMR) of CH4 and CO2 are achieved using of O2 as a reference gas. Shipborne FTIR-measurements of CO and data from SCIAMACHY/ENVISAT retrieved by the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS) retrieval algorithm show qualitatively the same latitudinal variations. WFMDOAS data of CH4, N2O and CO2 measured over sea exhibit a great spread. The spread …