Advancing Anion-Exchange-Membrane Water Electrolyzer Devices: Catalyst Layer Interactions, Degradation Pathways, and Operational Development

Water electrolyzers (WEs) are a key technology for a sustainable economy. When powered by renewable electricity, WEs produce green hydrogen, which can be used for energy, fertilizer, and industrial applications and thus displace fossil fuels. Pure-water anion-exchange-membrane (AEM) WEs offer the advantages of commercialized WE systems (high current density, low cross over, output gas compression, etc.) while enabling the use of less-expensive components and catalysts. However, current systems lack competitive performance and durability needed for commercialization, largely limited by the poor stability of anion-exchange polymers used in the membrane and catalyst layers. Further, while non-platinum-group-metal oxygen-evolution catalysts show excellent performance and durability in alkaline electrolyte, this has not transferred directly to pure-water AEMWEs. The following dissertation is a comprehensive analysis of the fundamental processes that dictate pure-water AEMWE performance and stability. Chapter I introduces AEMWEs in the context of industry-scale devices. Chapter II reports AEMWE cell performance comprising entirely of commercially available materials, detailing the key preparation, and operation techniques. In Chapter III, the structural stability and ionomer interactions of non-platinum-group-metal (non-PGM) anode catalysts are characterized. The results show catalyst electrical conductivity is key to obtaining high-performing systems and that many non-PGM catalysts restructure during operation, resulting in lower lifetimes. Chapter IV investigates ionomer degradation during device operation, revealing anode ionomer oxidation is the dominant degradation mechanism for all AEM-based electrolyzers tested. Improved device stability using oxidation-resistant catalyst layer binders is shown and new design strategies for advanced ionomer and catalyst layer development are provided. Chapter V provides a summary of the findings in Chapters III and IV and describes the future outlook for advanced catalyst layer development. Lastly, Chapter VI introduces advanced applications for AEMWE systems, detailing technical barriers and possible research approaches to developing AEM electrolyzers for impure-water splitting. These results significantly improve upon past understanding of pure water AEMWE devices by revealing the fundamental catalyst layer processes resulting in AEMWE device failure under relevant conditions, demonstrating a viable non-PGM catalyst for AEMWE operation, and illustrating underlying design rules for engineering anode catalyst/ionomer layers with higher performance and durability. This dissertation contains previously published and un-published co-authored materials

Three-Electrode Study of Electrochemical Ionomer Degradation Relevant to Anion-Exchange-Membrane Water Electrolyzers

Among existing water electrolysis (WE) technologies, anion-exchange-membrane water electrolyzers (AEMWEs) show promise for low-cost operation enabled by the basic solid-polymer electrolyte used to conduct hydroxide ions. The basic environment within the electrolyzer, in principle, allows the use of non-platinum-group metal catalysts and less-expensive cell components compared to acidic-membrane systems. Nevertheless, AEMWEs are still underdeveloped, and the degradation and failure modes are not well understood. To improve performance and durability, supporting electrolytes such as KOH and K2CO3 are often added to the water feed. The effect of the anion interactions with the ionomer membrane (particularly other than OH-), however, remains poorly understood. We studied three commercial anion-exchange ionomers (Aemion, Sustainion, and PiperION) during oxygen evolution (OER) at oxidizing potentials in several supporting electrolytes and characterized their chemical stability with surface-sensitive techniques. We analyzed factors including the ionomer conductivity, redox potential, and pH tolerance to determine what governs ionomer stability during OER. Specifically, we discovered that the oxidation of Aemion at the electrode surface is favored in the presence of CO32-/HCO3- anions perhaps due to the poor conductivity of that ionomer in the carbonate/bicarbonate form. Sustainion tends to lose its charge-carrying groups as a result of electrochemical degradation favored in basic electrolytes. PiperION seems to be similarly negatively affected by a pH drop and low carbonate/bicarbonate conductivity under the applied oxidizing potential. The insight into the interactions of the supporting electrolyte anions with the ionomer/membrane helps shed light on some of the degradation pathways possible inside of the AEMWE and enables the informed design of materials for water electrolysis

The Iowa Homemaker vol.6, no.2 Extra

Table of Contents An Invitation to Attend the Dedication of Home Economics Hall by Anna E. Richardson, page 1 In Our New Home at Last by Marcia E. Turner, page 2 Household Equipment by Eloise Davison, page 2 A Walk Around Campus by Vivian Jordan Brashear, page 3 Textiles and Clothing by Frances Sims, page 4 Child Care and Parent Training by Lydia Swanson, page 4 Applied Art by Joanna M. Hansen, page 5 Foods and Nutrition Department by Alma M. Riemenschneider, page 6 Institutional Management by Linda Spence Brown, page 7 Physical Education by Winifred R. Tilden, page 7 Home Economics Vocational Education by Marica E. Turner, page 8 The Department of Hygiene by Grace Magee, page 8 The Household Administration Department by Ruth M. Lindquist, page 9 Homemakers Department by Elizabeth M. Rivers, page

Methodological limitations of psychosocial interventions in patients with an implantable cardioverter-defibrillator (ICD) A systematic review

<p>Abstract</p> <p>Background</p> <p>Despite the potentially life-saving benefits of the implantable cardioverter-defibrillator (ICD), a significant group of patients experiences emotional distress after ICD implantation. Different psychosocial interventions have been employed to improve this condition, but previous reviews have suggested that methodological issues may limit the validity of such interventions. Aim: To review the methodology of previously published studies of psychosocial interventions in ICD patients, according to CONSORT statement guidelines for non-pharmacological interventions, and provide recommendations for future research.</p> <p>Methods</p> <p>We electronically searched the PubMed, PsycInfo and Cochrane databases. To be included, studies needed to be published in a peer-reviewed journal between 1980 and 2008, to involve a human population aged 18+ years and to have an experimental design.</p> <p>Results</p> <p>Twelve studies met the eligibility criteria. Samples were generally small. Interventions were very heterogeneous; most studies used cognitive behavioural therapy (CBT) and exercise programs either as unique interventions or as part of a multi-component program. Overall, studies showed a favourable effect on anxiety (6/9) and depression (4/8). CBT appeared to be the most effective intervention. There was no effect on the number of shocks and arrhythmic events, probably because studies were not powered to detect such an effect. Physical functioning improved in the three studies evaluating this outcome. Lack of information about the indication for ICD implantation (primary vs. secondary prevention), limited or no information regarding use of anti-arrhythmic (9/12) and psychotropic (10/12) treatment, lack of assessments of providers' treatment fidelity (12/12) and patients' adherence to the intervention (11/12) were the most common methodological limitations.</p> <p>Conclusions</p> <p>Overall, this review supports preliminary evidence of a positive effect of psychosocial interventions on anxiety and physical functioning in ICD patients. However, these initial findings must be interpreted cautiously because of important methodological limitations. Future studies should be designed as large RCTs, whose design takes into account the specific challenges associated with the evaluation of behavioural interventions.</p

Educating for change: A case for a pedagogy of desire in design education

Despite major inroads in demystifying creativity for the non-design disciplines, there has been very little movement in the design disciplines themselves beyond traditional paradigms. As argued in this paper, this is particularly noticeable in design education where traditional pedagogical approaches persist despite the emergence of new experimental pedagogies and the possibilities and opportunities they offer. In response, this paper describes what is revealed when a ‘pedagogy of desire’ is used as a critical lens to reflect on an experience of developing and implementing a first year interior design program involving first and second year undergraduate interior design and architecture students. Implications drawn from the review are presented and a case made for continuing experimentation and development of a pedagogy of desire for design learning and teaching