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.

Performance and Durability of Pure-Water-Fed Anion Exchange Membrane Electrolyzers Using Baseline Materials and Operation.

Water electrolysis powered by renewable electricity produces green hydrogen and oxygen gas, which can be used for energy, fertilizer, and industrial applications and thus displace fossil fuels. Pure-water anion-exchange-membrane (AEM) electrolyzers in principle offer the advantages of commercialized proton-exchange-membrane systems (high current density, low cross over, output gas compression, etc.) while enabling the use of less-expensive steel components and nonprecious metal catalysts. AEM electrolyzer research and development, however, has been limited by the lack of broadly accessible materials that provide consistent cell performance, making it difficult to compare results across studies. Further, even when the same materials are used, different pretreatments and electrochemical analysis techniques can produce different results. Here, we report an AEM electrolyzer comprising commercially available catalysts, membrane, ionomer, and gas-diffusion layers operating near 1.9 V at 1 A cm-2 in pure water. After the initial break in, the performance degraded by 0.67 mV h-1 at 0.5 A cm-2 at 55 °C. We detail the key preparation, assembly, and operation techniques employed and show further performance improvements using advanced materials as a proof-of-concept for future AEM-electrolyzer development. The data thus provide an easily reproducible and comparatively high-performance baseline that can be used by other laboratories to calibrate the performance of improved cell components, nonprecious metal oxygen evolution, and hydrogen evolution catalysts and learn how to mitigate degradation pathways.

Observation of Preferential Pathways for Oxygen Removal through Porous Transport Layers of Polymer Electrolyte Water Electrolyzers.

Understanding the relationships between porous transport layer (PTL) morphology and oxygen removal is essential to improve the polymer electrolyte water electrolyzer (PEWE) performance. Operando X-ray computed tomography and machine learning were performed on a model electrolyzer at different water flow rates and current densities to determine how these operating conditions alter oxygen transport in the PTLs. We report a direct observation of oxygen taking preferential pathways through the PTL, regardless of the water flow rate or current density (1-4 A/cm2). Oxygen distribution in the PTL had a periodic behavior with period of 400 µm. A computational fluid dynamics model was used to predict oxygen distribution in the PTL showing periodic oxygen front. Observed oxygen distribution is due to low in-plane PTL tortuosity and high porosity enabling merging of oxygen bubbles in the middle of the PTL and also due to aerophobicity of the layer.

The St. Jude STEM Clubs: An Afterschool STEM Club for Upper Elementary School Students in Memphis, TN.

Informal science, technology, engineering, and math (STEM) programs are important tools for broadening participation in STEM careers. The St. Jude STEM Club (SJSC) is a 10-week afterschool STEM club focused on real-world problems in pediatric cancer research and designed for students in the fifth grade. The SJSC is conducted in partnership with the Shelby County Schools (SCS), an urban school district that encompasses Memphis, TN and serves a disproportionate number of students from underrepresented backgrounds in science. In this report, we provide details on the club logistics, curriculum, pilot data and outcomes related to club impact on student attitudes towards science, and challenges and limitations of the program. Participants in the program reported significantly higher rates of STEM engagement, STEM identity, critical thinking, perseverance, and relationships with peers and adults compared to national normative data. This program description is intended to serve as a resource for other institutions wanting to use a similar strategy to broaden participation in STEM careers.

Understanding How Adolescents Think about the HPV Vaccine.

Despite educational efforts, Tennessee human papillomavirus (HPV) vaccination rates are 43%, among the lowest in the United States. This study examined how adolescents think about the HPV vaccine to identify patterns and misconceptions to enhance educational efforts. Adolescents (ages 11-12) (N = 168) responded to open-ended questions regarding their thinking about the HPV vaccine. Data were analyzed and interpreted using qualitative thematic analysis. Three domains of themes emerged from responses: (1) characteristics of HPV vaccination, (2) knowledge-related themes, and (3) beliefs-related themes. Prevention of HPV and cancer was the most referenced characteristic of HPV vaccination followed by HPV vaccine rates and HPV vaccine efficacy. Student inquiries were mostly centered on HPV vaccine composition, administration, duration and how the vaccine interacts with the body. Some responses indicated a desire for more information about HPV not specific to the HPV vaccine. Overall, adolescent attitudes were positive towards the HPV vaccine. This study highlights specific questions adolescents have about the vaccine that can be used to tailor future HPV educational efforts, empowering adolescents with the knowledge to be more active students in the decision-making process. In addition, the potential for adolescents to serve as community advocates for the vaccine should be considered for future interventions.

Evaluation of the St. Jude Cancer Education for Children Program on Cancer Risk Awareness, Attitudes, and Behavioral Intentions Among Fourth-Grade Science Students: Comparisons Between Racially Identifiable/High-Poverty Schools and Racially Diverse/Affluent Schools.

The St. Jude Cancer Education for Children Program (SJCECP) aims to teach children about cancer and cancer control behaviors. During the 2012-2014 academic year, we conducted a pilot evaluation of the SJCECP curriculum to determine its impact on cancer risk awareness, attitudes, and behavioral intentions among fourth-grade students participating in the program. Nine local schools and 426 students from the Memphis area participated in the program evaluation. The results of this study show an increase in fourth-grade students' overall cancer risk factor awareness, attitudes, and behavioral intentions after participation in the intervention. The study also compared the mean change score for unaware students (e.g., those whose mean item score was < 3.5 on the pre-test) between students from racially identifiable/high-poverty schools (school group 1; six schools) and racially diverse/affluent schools (school group 2; three schools). Comparison of the mean change score for unaware students between school group 1 and school group 2 showed that increases in overall cancer risk factor awareness in school group 1 were higher than the increases of unaware students seen in school group 2; however, no differences between the changes in attitudes towards cancer risk factors and cancer control intentions and behaviors between the school groups were observed. We conclude that the SJCECP curriculum is successful in promoting cancer risk factor awareness, positive attitudes towards cancer risk factors, and increased cancer control intentions and behaviors among students at the fourth-grade level regardless of school demographics.

Controlling the Distribution of Perfluorinated Sulfonic Acid Ionomer with Elastin-like Polypeptide.

Proton-exchange-membrane (PEM)-based devices are promising technologies for hydrogen production and electricity generation. Currently, the amount of expensive platinum catalyst used in these devices must be reduced to be cost-competitive with other technologies. These devices typically contain Nafion ionomer thin films in the catalyst layers, which are responsible for transporting protons and gaseous species to and from electrochemically active sites. The morphology of the Nafion ionomer thin films in the catalyst layers with reduced platinum loading is impacted by interactions with the catalyst and the confinement to nanometer thicknesses, which leads to performance losses in PEM-based devices. In this study, an elastin-like polypeptide (ELP) is designed to modulate the morphology of Nafion ionomer on platinum surfaces. The ELP shows an ability to assemble into a monolayer on platinum and change the ionomer interaction with platinum, thereby modifying its thin-film structure and improving the Nafion ionomer coverage. As a proof of concept, an ELP-modified catalyst ink was prepared and morphological differences were observed. Overall, we discovered an engineered ELP that can modulate the ionomer-catalyst interface in the electrodes of PEM-based devices.

A non-precious metal hydrogen catalyst in a commercial polymer electrolyte membrane electrolyser.

We demonstrate the translation of a low-cost, non-precious metal cobalt phosphide (CoP) catalyst from 1 cm2 lab-scale experiments to a commercial-scale 86 cm2 polymer electrolyte membrane (PEM) electrolyser. A two-step bulk synthesis was adopted to produce CoP on a high-surface-area carbon support that was readily integrated into an industrial PEM electrolyser fabrication process. The performance of the CoP was compared head to head with a platinum-based PEM under the same operating conditions (400 psi, 50 °C). CoP was found to be active and stable, operating at 1.86 A cm-2 for >1,700 h of continuous hydrogen production while providing substantial material cost savings relative to platinum. This work illustrates a potential pathway for non-precious hydrogen evolution catalysts developed in past decades to translate to commercial applications.

Perspectives on Low-Temperature Electrolysis and Potential for Renewable Hydrogen at Scale.

Hydrogen is an important part of any discussion on sustainability and reduction in emissions across major energy sectors. In addition to being a feedstock and process gas for many industrial processes, hydrogen is emerging as a fuel alternative for transportation applications. Renewable sources of hydrogen are therefore required to increase in capacity. Low-temperature electrolysis of water is currently the most mature method for carbon-free hydrogen generation and is reaching relevant scales to impact the energy landscape. However, costs still need to be reduced to be economical with traditional hydrogen sources. Operating cost reductions are enabled by the recent availability of low-cost sources of renewable energy, and the potential exists for a large reduction in capital cost withmaterial and manufacturing optimization. This article focuses on the current status and development needs by component for the low-temperature electrolysis options.

Dynamic surface self-reconstruction is the key of highly active perovskite nano-electrocatalysts for water splitting.

The growing need to store increasing amounts of renewable energy has recently triggered substantial R&D efforts towards efficient and stable water electrolysis technologies. The oxygen evolution reaction (OER) occurring at the electrolyser anode is central to the development of a clean, reliable and emission-free hydrogen economy. The development of robust and highly active anode materials for OER is therefore a great challenge and has been the main focus of research. Among potential candidates, perovskites have emerged as promising OER electrocatalysts. In this study, by combining a scalable cutting-edge synthesis method with time-resolved X-ray absorption spectroscopy measurements, we were able to capture the dynamic local electronic and geometric structure during realistic operando conditions for highly active OER perovskite nanocatalysts. Ba0.5Sr0.5Co0.8Fe0.2O3-δ as nano-powder displays unique features that allow a dynamic self-reconstruction of the material's surface during OER, that is, the growth of a self-assembled metal oxy(hydroxide) active layer. Therefore, besides showing outstanding performance at both the laboratory and industrial scale, we provide a fundamental understanding of the operando OER mechanism for highly active perovskite catalysts. This understanding significantly differs from design principles based on ex situ characterization techniques.

St. Jude Cancer Education for Children Program: The Impact of a Teacher-Led Intervention on Student Knowledge Gains.

In 2006, St. Jude Children's Research Hospital (Memphis, Tennessee) began developing a school-based outreach program known as the St. Jude Cancer Education for Children Program (SJCECP). The aim of this program is to teach Memphis-area children about cells, cancer, and healthy habits that can prevent the development of cancer in adulthood. Initial plans for delivery of the program was for St. Jude staff to present the program at local schools. This plan for disseminating instruction was not feasible due to the limited availability of St. Jude staff. As a next step, during the 2012-2014 academic years, we conducted a study entitled SJCECP2, utilizing the SJCECP curriculum, with the objective of evaluating the impact of the educational intervention on knowledge acquisition and retention among fourth-grade students participating in a modified, teacher-led version of the program. Eighteen teachers and 426 students from 10 local schools in the greater Memphis area participated in the program evaluation. This study used a single-group, pre-test/post-test design to determine the impact of the SJCECP intervention on changes in knowledge scores among fourth-grade students. Testing was on cells, cancer, and healthy living. The mean scores increased from 6.45 to 8.12, 5.99 to 7.65, and 5.92 to 7.96 on cell, cancer, and health behaviors units, respectively (all p values <.001). Preliminary evidence suggests that the SJCECP2 intervention is a useful tool for teachers to improve student knowledge of knowledge of cells, cancer, and healthy living concepts at the fourth-grade level.

The St. Jude Cancer Education for Children Program Pilot Study: Determining the Knowledge Acquisition and Retention of 4th-Grade Students.

In 2006, St. Jude Children's Research Hospital began developing a school-based outreach program known as the St. Jude Cancer Education for Children Program (SJCECP). The program aimed to teach children about cancer and healthy habits that can prevent the formation of cancers into adulthood. During the 2010-2011 academic years, we conducted a pilot evaluation of the SJCECP curriculum, with the primary objective of evaluating the impact of the intervention on knowledge acquisition and retention among 4th-grade students participating in the program. Seven local schools and 481 students from the Memphis area participated in the program evaluation. The results of this study show that 4th-grade students are able to acquire gains in knowledge related to cells, cancer, and healthy living after receiving the SJCECP intervention. We conclude that the program can be a useful tool for improving knowledge of cancer concepts at the 4th-grade level.

Ultralow charge-transfer resistance with ultralow Pt loading for hydrogen evolution and oxidation using Ru@Pt core-shell nanocatalysts.

We evaluated the activities of well-defined Ru@Pt core-shell nanocatalysts for hydrogen evolution and oxidation reactions (HER-HOR) using hanging strips of gas diffusion electrode (GDE) in solution cells. With gas transport limitation alleviated by micro-porous channels in the GDEs, the charge transfer resistances (CTRs) at the hydrogen reversible potential were conveniently determined from linear fit of ohmic-loss-corrected polarization curves. In 1 M HClO4 at 23 °C, a CTR as low as 0.04 Ω cm(-2) was obtained with only 20 µg cm(-2) Pt and 11 µg cm(-2) Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio. Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol(-1). Using the Ru@Pt catalyst with total metal loadings <50 µg cm(-2) for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm(-2) Pt black.

Combinatorial search for improved metal oxide oxygen evolution electrocatalysts in acidic electrolytes.

A library of electrocatalysts for water electrolysis under acidic conditions was created by ink jet printing metal oxide precursors followed by pyrolysis in air to produce mixed metal oxides. The compositions were then screened in acidic electrolytes using a pH sensitive fluorescence indicator that became fluorescent due to the pH change at the electrode surface because of the release of protons from water oxidation. The most promising materials were further characterized by measuring polarization curves and Tafel slopes as anodes for water oxidation. Mixed metal oxides that perform better than the iridium oxide standard were identified.

Pityrosporum folliculitis: diagnosis and management in 6 female adolescents with acne vulgaris.

BACKGROUND: Pityrosporum folliculitis is a common inflammatory skin disorder that may mimic acne vulgaris. Some adolescents with recalcitrant follicular pustules or papules may have acne and Pityrosporum folliculitis simultaneously. Clinical response is dependent on treating both conditions. OBJECTIVES: To demonstrate the similarity in clinical manifestation between acne vulgaris and Pityrosporum folliculitis, the benefit of potassium hydroxide preparation, and the benefit of appropriate antifungal therapy. PATIENTS: We describe 6 female adolescents with concurrent Pityrosporum folliculitis infection and acne vulgaris. INTERVENTION: A potassium hydroxide examination was performed on all 6 patients from the exudate of follicular pustules exhibiting spores consistent with yeast. All patients were treated with oral antifungals, and 5 of the 6 patients were also treated with topical antifungals. RESULTS: Six of 6 patients improved with antifungal treatment. All patients also required some ongoing therapy for their acne. CONCLUSIONS: These patients demonstrate that follicular papulopustular inflammation of the face, back, and chest may be due to a combination of acne vulgaris and Pityrosporum folliculitis, a common yet less frequently identified disorder. Symptoms often wax and wane depending on the patient's activities, time of the year, current treatment regimens, and other factors. Pityrosporum folliculitis will often worsen with traditional acne therapy and dramatically respond to antifungal therapy.