Gerhard Swiegers

Gortex-Based Gas Diffusion Electrodes with Unprecedented Resistance to Flooding and Leaking

Publisher: American Chemical Society (ACS)

Date: 27-07-2018

DOI: 10.1021/ACSAMI.8B05358

Abstract: A significant and long-standing problem in electrochemistry has demanded the need for gas diffusion electrodes that are "flood-proof" and "leak-proof" when operated with a liquid electrolyte. The absence of a solution to this problem has, effectively, made it unviable to use gas diffusion electrodes in many electrochemical manufacturing processes, especially as " gas-depolarized" counter electrodes with significantly decreased energy consumption. In this work, Gortex membranes (also known as expanded PTFE or ePTFE) have been studied as novel, leak-proof substrates for gas diffusion electrodes [PTFE = poly(tetrafluoroethylene)]. We report the fabrication, characterization, and operation of gas diffusion electrodes comprising finely pored Gortex overcoated with 10% Pt on Vulcan XC72, PTFE binder, and a fine Ni mesh as a current carrier. Capillary flow porometry indicated that the electrodes only flooded/leaked when the excess of pressure on their liquid-side over their gas-side was 5.7 atm. This is more than an order of magnitude greater than any previous gas diffusion electrode. The Gortex electrodes were tested as hydrogen- and oxygen-depolarized anodes and cathodes in an alkaline fuel cell in which the liquid electrolyte was pressurized to 0.5-1.5 atm above the gas pressures. Despite the record high electrolyte pressure, the electrodes, which had Pt loadings of only 0.075 mg Pt/cm

Sustained Water Oxidation by Mn4O4 (7+) Core Complexes Inspired by Oxygenic Photosynthesis

Publisher: American Chemical Society (ACS)

Date: 02-07-2009

DOI: 10.1021/IC9006982

Abstract: The bioinspired Mn-oxo cubane complex, [Mn(4)O(4)L(6)](+) 1b(+) (L = (p-MeO-Ph)(2)PO(2)), is a model of the photosynthetic O(2)-evolving complex. It is able to electro-oxidize water at 1.00 V (vs Ag/AgCl) under illumination by UV-visible light when suspended in a proton-conducting membrane (Nafion) coated onto a conducting electrode. Electrochemical measurements, and UV-visible, NMR, and EPR spectroscopies are interpreted to indicate that 1b(+) is the dominant electro-active species in the Nafion, both before and after catalytic cycling, and thus correlates closely with activity. The observation of a possible intermediate and free phosphinate ligand within the Nafion suggests a catalytic mechanism involving photolytic disruption of a phosphinate ligand, followed by O(2) formation, and subsequent reassembly of the cubane structure. Several factors that influence catalytic turnover such as the applied potential, illumination wavelength, and energy have been examined in respect of attaining optimum catalytic activity. Catalytic turnover frequencies of 20-270 molecules O(2) h(-1) catalyst(-1) at an overpotential of 0.38 V plus light (275-750 nm) and turnovers numbers >1000 molecules O(2) catalyst(-1) are observed. The 1b(+)-Nafion system is among the most active and durable molecular water oxidation catalysts known.

Homogeneous Catalysts with a Mechanical (Machine-like) Action

Publisher: Wiley

Date: 28-04-2009

DOI: 10.1002/CHEM.200802396

Abstract: Chemical reactions may be controlled by either: 1) the minimum threshold energy that must be overcome during collisions between reactant molecules/atoms (the activation energy, E(a)), or: 2) the rate at which reactant collisions occur (the collision frequency, A)--for reactions with low E(a). 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. In this work we examine the machine-like nature of the action in various abiological mechanical catalysts and consider the implications for mimicry of biological catalysts.

A readily-prepared electrocatalytic coating that is more active than platinum for hydrogen generation in 1 M strong acid

Publisher: Royal Society of Chemistry (RSC)

Date: 2004

DOI: 10.1039/B311674C

Hydrogen generation using PPy-FMS modified PVDF membrane and other substrates

Publisher: Elsevier BV

Date: 09-2005

DOI: 10.1016/J.SYNTHMET.2005.07.022

Redox-active conducting polymers incorporating ferrocenes 2. Preparation and characterisation of polypyrroles containing propyl- and butyl-tethered[1.1]ferrocenophane

Publisher: Elsevier BV

Date: 02-2004

DOI: 10.1016/J.ELECTACTA.2003.08.031

Microwave-assisted synthesis of Pt/CNT nanocomposite electrocatalysts for PEM fuel cells

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B9NR00140A

Demetallatation of electrochemically polymerised Mn porphyrin anion / PEDOT composites under light-illumination

Publisher: Elsevier BV

Date: 06-2017

DOI: 10.1016/J.SYNTHMET.2017.04.010

Redox-active conducting polymers incorporating ferrocenes. Preparation, characterization and bio-sensing properties of ferrocenylpropyl and -butyl polypyrroles

Publisher: Elsevier BV

Date: 10-2002

DOI: 10.1016/S0013-4686(02)00446-2

Synergistic Amplification of Oxygen Generation in (Photo)Catalytic Water Splitting by a PEDOT/Nano‐Co₃O₄/MWCNT Thin Film Composite

Publisher: Wiley

Date: 10-01-2020

DOI: 10.1002/CCTC.201902244

Studies of poly(3,4-ethylenedioxythiophene) (PEDOT) films containing cationic Mn porphyrins. A loading-dependent demetalation of Mn(III)TPP in PEDOT (Mn(III)TPP=5,10,15,20-tetraphenylporphyrinato mang

Publisher: World Scientific Pub Co Pte Lt

Date: 12-2016

DOI: 10.1142/S1088424616501285

Abstract: Thin films of vapor-phase polymerized PEDOT incorporating various cationic Mn porphyrins were assessed for water oxidation catalysis under light illumination. Only Mn(III)TPP/PEDOT displayed a notable photocurrent and this was, counter-intuitively, greatest at the lowest loading levels examined. Studies revealed that a proportion of the Mn(III)TPP within the PEDOT became demetalated during polymerization, leaving free and protonated TPP. Despite the presence of an excess of chemical oxidant during the polymerization step, the Mn(III) ion was reduced — likely under the influence of light — to Mn(II), which was labilized out of the film. Whereas PEDOT films loaded with anionic Mn porphyrins may be active and selective water oxidation photocatalysts, their analogs containing cationic Mn porphyrins, like Mn(III)TPP, are catalytically inert.

Current status of membraneless water electrolysis cells

Publisher: Elsevier BV

Date: 04-2022

DOI: 10.1016/J.COELEC.2021.100881

Bioinspired Catalysis

Publisher: Wiley

Date: 05-12-2012

DOI: 10.1002/9781118310083.CH7

Preparation of platinum inverse opals using self-assembled templates and their application in methanol oxidation

Publisher: Elsevier BV

Date: 06-2007

DOI: 10.1016/J.MATLET.2007.01.096

Stable and Efficient Photoinduced Charge Transfer of MnFe2O4/Polyaniline Photoelectrode in Highly Acidic Solution

Publisher: MDPI AG

Date: 22-12-2021

DOI: 10.3390/COLLOIDS6010001

Abstract: Tailoring conductive polymers with inorganic photocatalysts, which provide photoinduced electron-hole generation, have significantly enhanced composites leading to excellent photoelectrodes. In this work, MnFe2O4 nanoparticles prepared by a hydrothermal method were combined with polyaniline to prepare mixed (hybrid) slurries, which were cast onto flexible FTO to prepare photoelectrodes. The resulting photoelectrodes were characterized by XRD, FESEM, HRTEM and UV-VIS. The photoelectrochemical performance was investigated by linear sweep voltammetry and chrono erometry. The photocurrent achieved by MnFe2O4/Polyaniline was 400 μA/cm2 at 0.8 V vs. Ag/AgCl in Na2SO4 (pH = 2) at 100 mW/cm2, while polyaniline alone achieved only 25 μA/cm2 under the same conditions. The best MnFe2O4/Polyaniline displayed an incident photon-to-current conversion efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) of 60% at 405 nm wavelength, and 0.17% at 0.8 V vs. Ag/AgCl, respectively. High and stable photoelectrochemical performance was achieved for more than 900 s in an acidic environment.

Electrochemical investigation of Mn4O4-cubane water-oxidizing clusters

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B901419E

Abstract: High valence states in manganese clusters are a key feature of the function of one of the most important catalysts found in nature, the water-oxidizing complex of photosystem II. We describe a detailed electrochemical investigation of two bio-inspired manganese-oxo complexes, [Mn(4)O(4)L(6)] (L = diphenylphosphinate (1) and bis(p-methoxyphenyl)phosphinate (2)), in solution, attached to an electrode surface and suspended within a Nafion film. These complexes contain a cubic [Mn(4)O(4)](6+) core stabilized by phosphinate ligands. They have previously been shown to be active and durable photocatalysts for the oxidation of water to dioxygen. A comparison of catalytic photocurrent generated by films deposited by two methods of electrode immobilization reveals that doping of the catalyst in Nafion results in higher photocurrent than was observed for a solid layer of cubane on an electrode surface. In dichloromethane solution, and under conditions of cyclic voltammetry, the one-electron oxidation processes 1/1(+) and 2/2(+) were found to be reversible and quasi-reversible, respectively. Some decomposition of 1(+) and 2(+) was detected on the longer timescale of bulk electrolysis. Both compounds also undergo a two-electron, chemically irreversible reduction in dichloromethane, with a mechanism that is dependent on scan rate and influenced by the presence of a proton donor. When immersed in aqueous electrolyte, the reduction process exhibits a limited level of chemical reversibility. These data provide insights into the catalytic operation of these molecules during photo-assisted electrolysis of water and highlight the importance of the strongly electron-donating ligand environment about the manganese ions in the ability of the cubanes to photocatalyze water oxidation at low overpotentials.

High-performing catalysts for energy-efficient commercial alkaline water electrolysis

Publisher: Royal Society of Chemistry (RSC)

Date: 2023

DOI: 10.1039/D2SE01197B

Abstract: High-performing, durable electrocatalysts, capable of maintaining industrial current densities (200–700 mA cm −2 ), are needed.

Synergistic Amplification of Water Oxidation Catalysis on Pt by a Thin-Film Conducting Polymer Composite

Publisher: American Chemical Society (ACS)

Date: 16-07-2018

DOI: 10.1021/ACSAEM.8B00728

An efficient bifunctional electrocatalyst of methanol oxidation

Publisher: American Chemical Society (ACS)

Date: 29-08-2007

DOI: 10.1021/OM070224R

Conducting-Polymer Nanocomposites as Synergistic Supports That Accelerate Electro-Catalysis: PEDOT/Nano Co3O4/rGO as a Photo Catalyst of Oxygen Production from Water

Publisher: MDPI AG

Date: 12-09-2021

DOI: 10.3390/JCS5090245

Abstract: This work describes how conducting polymer nanocomposites can be employed as synergistic supports that significantly accelerate the rate of electro-catalysis. The nanocomposite PEDOT/nano-Co3O4/rGO is discussed as an ex le in this respect, which is specific for photo electro-catalytic oxygen (O2) generation from water using light (PEDOT = poly (3,4-ethylenedioxythiophene) rGO = reduced graphene oxide). We show that the conducting polymer PEDOT and the conductive additive rGO may be used to notably lify the rate of O2-generation from water by the nano catalyst, Co3O4. A composite film containing the precise molar ratio 7.18 (C PEDOT):1 (Co):5.18 (C rGO) exhibited high photocatalytic activity (pH 12) for the oxygen evolution reaction (OER) at 0.80 V (vs. Ag/AgCl), with a current density of 1000 ± 50 μA/cm2 (including a photocurrent of 500 μA/cm2), achieved after h of operation under illumination with a light of intensity 0.25 sun. By comparison, the best industrial catalyst, Pt, yielded a much lower 150 μA/cm2 under the same conditions. Oxygen gas was the sole product of the reaction.

A readily-prepared, convergent, oxygen reduction electrocatalyst

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B707799H

Abstract: Monomeric cobalt(II) tetraphenylporphyrin immobilized in high concentrations within vapour-phase polymerized polypyrrole deposited on an ITO electrode catalyzes the 4-electron reduction of dioxygen to water, a reaction requiring concerted action by two separate catalytic groups.

Application of Conducting Polymers in Solar Water-Splitting Catalysis

Publisher: Springer International Publishing

Date: 2016

DOI: 10.1007/978-3-319-26893-4_11

Novel ACNT arrays based MEA structure-nano-Pt loaded ACNT/Nafion/ACNT for fuel cell applications

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B925591E

Abstract: A novel designed free-standing, sandwich-structured membrane electrode assembly (MEA), nano-Pt loaded (0.142 mg cm(-2)) ACNT/Nafion/ACNT via the attachment of two sets of aligned CNT array electrode structures to opposite sides of a Nafion PEM membrane exhibits significantly improved performance compared to commercially available Pt/CB catalysts used in PEM fuel cell applications.

Synergistic amplification of (photo)catalytic oxygen and hydrogen generation from water by thin-film polypyrrole composites

Publisher: Elsevier BV

Date: 07-2020

DOI: 10.1016/J.MCAT.2020.110955

An electrochemical cell with Gortex-based electrodes capable of extracting pure hydrogen from highly dilute hydrogen–methane mixtures

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C7EE02236K

Abstract: In this work we report a novel liquid–acid electrochemical cell containing Gortex-based gas diffusion electrodes, layered with suitable catalysts and current collectors, that is capable of sustainably extracting pure hydrogen from methane mixtures containing as little as 5% hydrogen.

A new class of bubble-free water electrolyzer that is intrinsically highly efficient

Publisher: Elsevier BV

Date: 09-2019

DOI: 10.1016/J.IJHYDENE.2019.07.100

Towards hydrogen energy: Progress on catalysts for water splitting

Publisher: CSIRO Publishing

Date: 2012

DOI: 10.1071/CH12048

Abstract: This article reviews some of the recent work by fellows and associates of the Australian Research Council Centre of Excellence for Electromaterials Science (ACES) at Monash University and the University of Wollongong, as well as their collaborators, in the field of water oxidation and reduction catalysts. This work is focussed on the production of hydrogen for a hydrogen-based energy technology. Topics include: (1) the role and apparent relevance of the cubane-like structure of the Photosystem II Water Oxidation Complex (PSII-WOC) in non-biological homogeneous and heterogeneous water oxidation catalysts, (2) light-activated conducting polymer catalysts for both water oxidation and reduction, and (3) porphyrin-based light harvesters and catalysts.

A Porphyrin‐Doped Polymer Catalyzes Selective, Light‐Assisted Water Oxidation in Seawater

Publisher: Wiley

Date: 20-01-2012

DOI: 10.1002/ANIE.201107355

Interaction of graphene, MnO , and Ca2+ for enhanced biomimetic, ‘bubble-free’ oxygen evolution reaction at mild pH

Publisher: Elsevier BV

Date: 08-2021

DOI: 10.1016/J.IJHYDENE.2021.06.094

Using a principle of heterogeneous catalysis to achieve enzyme-like molecular catalysis

Publisher: Elsevier BV

Date: 07-2003

DOI: 10.1016/S0162-0134(03)80648-7

Time-Dependent (Mechanical), Nonbiological Catalysis. 3. A Readily Prepared, Convergent, Oxygen-Reduction Electrocatalyst

Publisher: Wiley

Date: 25-02-2008

DOI: 10.1002/9780470384190.CH13

Time-Dependent (Mechanical), Nonbiological Catalysis. 2. Highly Efficient, Biomimetic Hydrogen-Generating Electrocatalysts

Publisher: Wiley

Date: 25-02-2008

DOI: 10.1002/9780470384190.CH12

Polypyrrole/Co-tetraphenylporphyrin as a fuel cell electrocatalyst modified carbon fibre paper of oxygen reduction

Publisher: Elsevier BV

Date: 04-2008

DOI: 10.1016/J.ELECOM.2008.01.032

Alkaline Fuel Cells with Novel Gortex-Based Electrodes are Powered Remarkably Efficiently by Methane Containing 5% Hydrogen

Publisher: Wiley

Date: 26-10-2018

DOI: 10.1002/AENM.201702285

Photocatalytic Hydrogen Generation from pH-Neutral Water by a Flexible Tri-Component Composite

Publisher: Springer Science and Business Media LLC

Date: 20-10-2020

DOI: 10.1007/S10562-020-03427-1

Nano-Pt Modified Aligned Carbon Nanotube Arrays Are Efficient, Robust, High Surface Area Electrocatalysts

Publisher: American Chemical Society (ACS)

Date: 22-03-2008

DOI: 10.1021/CM703471X

Designed conducting polymer composites that facilitate long-lived, light-driven oxygen and hydrogen evolution from water in a photoelectrochemical concentration cell (PECC)

Publisher: MDPI AG

Date: 14-12-2019

DOI: 10.3390/JCS3040108

Abstract: Light-driven water-splitting to generate hydrogen and oxygen from water is typically carried out in an electrochemical cell with an external voltage greater than 1.23 V applied between the electrodes. In this work, we examined the use of a concentration/chemical bias as a means of facilitating water-splitting under light illumination without the need for such an externally applied voltage. Such a concentration bias was created by employing a pH differential in the liquid electrolytes within the O2-generating anode half-cell and the H2-generating cathode half-cell. A novel, stretchable, highly ion-conductive polyacrylamide CsCl hydrogel was developed to connect the two half-cells. The key feature of the cell was the half-cell electrodes, which comprised thin-film conducting polymer composites that were previously designed to maximize light-driven catalysis at moderate pH. Upon being connected with the hydrogel in the presence of light irradiation (0.25 sun intensity on each electrode), the half-cells spontaneously produced hydrogen and oxygen from water, without the need for an externally applied voltage bias greater than 1.23 V. The cell operated reliably and efficiently for 14 h of continuous testing. These results demonstrate the fundamental feasibility of light-driven water-splitting in a photoelectrochemical concentration cell when employing electrodes that operate efficiently at moderate pH, even with low levels of light illumination. The designed conducting polymer composites proved ideal in that regard.

A high-performance capillary-fed electrolysis cell promises more cost-competitive renewable hydrogen

Publisher: Springer Science and Business Media LLC

Date: 15-03-2022

DOI: 10.1038/S41467-022-28953-X

Abstract: Renewable, or green , hydrogen will play a critical role in the decarbonisation of hard-to-abate sectors and will therefore be important in limiting global warming. However, renewable hydrogen is not cost-competitive with fossil fuels, due to the moderate energy efficiency and high capital costs of traditional water electrolysers. Here a unique concept of water electrolysis is introduced, wherein water is supplied to hydrogen- and oxygen-evolving electrodes via capillary-induced transport along a porous inter-electrode separator, leading to inherently bubble-free operation at the electrodes. An alkaline capillary-fed electrolysis cell of this type demonstrates water electrolysis performance exceeding commercial electrolysis cells, with a cell voltage at 0.5 A cm −2 and 85 °C of only 1.51 V, equating to 98% energy efficiency, with an energy consumption of 40.4 kWh/kg hydrogen (vs. ~47.5 kWh/kg in commercial electrolysis cells). High energy efficiency, combined with the promise of a simplified balance-of-plant, brings cost-competitive renewable hydrogen closer to reality.

A light-assisted, polymeric water oxidation catalyst that selectively oxidizes seawater with a low onset potential

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3SC50812A

Photocatalytic oxygen evolution from non-potable water by a bioinspired molecular water oxidation catalyst

Publisher: Elsevier BV

Date: 17-02-2011

DOI: 10.1016/J.MOLCATA.2011.02.006

Preparation, characterisation and biosensor application of conducting polymers based on ferrocene substituted thiophene and terthiophene

Publisher: Elsevier BV

Date: 07-2002

DOI: 10.1016/S0013-4686(02)00136-6

Synergistic amplification of catalytic hydrogen generation by a thin-film conducting polymer composite

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8CY00780B

Abstract: The presence of PEDOT in a thin-film containing nano-Ni and rGO lifies catalytic hydrogen generation to exceed that by Pt.

Insights into the phenomenon of ‘bubble-free’ electrocatalytic oxygen evolution from water

Publisher: Royal Society of Chemistry (RSC)

Date: 2021

DOI: 10.1039/D0SE01633K

Abstract: Understanding of the operating mechanism of a ‘breathable’ water-splitting electrode, which extracts evolved gas without forming bubbles, is advanced.

Industry Laureate Fellowships - Grant ID: IL230100173

Start Date: 07-2023

End Date: 06-2028

Amount: $3,689,641.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0559629

Start Date: 2005

End Date: 12-2008

Amount: $361,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0665523

Start Date: 01-2006

End Date: 12-2009

Amount: $392,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP130101135

Start Date: 02-2014

End Date: 02-2017

Amount: $305,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP210301410

Start Date: 03-2023

End Date: 02-2026

Amount: $386,356.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0989652

Start Date: 09-2009

End Date: 02-2015

Amount: $610,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0771700

Start Date: 01-2007

End Date: 12-2010

Amount: $292,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0343586

Start Date: 2003

End Date: 12-2007

Amount: $682,275.00

Funder: Australian Research Council

ARC Centres Of Excellence - Grant ID: CE0348245

Start Date: 09-2003

End Date: 06-2005

Amount: $7,306,885.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354535

Start Date: 2004

End Date: 12-2004

Amount: $10,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE170100023

Start Date: 03-2017

End Date: 06-2018

Amount: $650,000.00

Funder: Australian Research Council