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The Achilles' heel of iron-based catalysts during oxygen reduction in an acidic medium
Choi, Chang Hyuck,Lim, Hyung-Kyu,Chung, Min Wook,Chon, Gajeon,Ranjbar Sahraie, Nastaran,Altin, Abdulrahman,Sougrati, Moulay-Tahar,Stievano, Lorenzo,Oh, Hyun Seok,Park, Eun Soo,Luo, Fang,Strasser, Pete The Royal Society of Chemistry 2018 ENERGY AND ENVIRONMENTAL SCIENCE Vol.11 No.11
<P>For catalysing dioxygen reduction, iron-nitrogen-carbon (Fe-N-C) materials are today the best candidates to replace platinum in proton-exchange membrane fuel cell (PEMFC) cathodes. Despite tremendous progress in their activity and site-structure understanding, improved durability is critically needed but challenged by insufficient understanding of their degradation mechanisms during operation. Here, we show that FeNxCy moieties in a representative Fe-N-C catalyst are structurally stable but electrochemically unstable when exposed in an acidic medium to H2O2, the main oxygen reduction reaction (ORR) byproduct. We reveal that exposure to H2O2 leaves iron-based catalytic sites untouched but decreases their turnover frequency (TOF) <I>via</I> oxidation of the carbon surface, leading to weakened O2-binding on iron-based sites. Their TOF is recovered upon electrochemical reduction of the carbon surface, demonstrating the proposed deactivation mechanism. Our results reveal for the first time a hitherto unsuspected key deactivation mechanism during the ORR in an acidic medium. This study identifies the N-doped carbon surface as the Achilles' heel during ORR catalysis in PEMFCs. Observed in acidic but not in alkaline electrolytes, these insights suggest that durable Fe-N-C catalysts are within reach for PEMFCs if rational strategies minimizing the amount of H2O2 or reactive oxygen species (ROS) produced during the ORR are developed.</P>
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Modified Research Utilization Questionnaire: Development and Validation Study among Italian Nurses
Rosario Caruso,Anna M. Grugnetti,Umberto Pastore,Federica Dellafiore,Francesco Pittella,Davide Ausili,Alessandro Stievano,Cristina Arrigoni 한국간호과학회 2019 Asian Nursing Research Vol.13 No.1
Purpose: The purpose of this study was to develop the modified research utilization questionnaire (MRUQ) and to establish its content and face validity, construct validity, and reliability. Methods: This study has a multiphase (three phases), methodological, and cross-sectional design. First, research utilization questionnaire (RUQ) was translated into Italian, which is the target language to develop the M-RUQ. Second, the RUQ psychometric proprieties were assessed using exploratory factorial analysis to identify ambiguous or problematic items (e.g., cross-loadings) (cross-sectional sampling A). The RUQ modification (i.e., item deleting, wording modification, and scoring procedure) represented the development of the M-RUQ among Italian nurses. The third phase was aimed to confirm the construct validity of the M-RUQ and to test its stability and internal consistency (crosssectional sampling B). Results: This study's findings show that M-RUQ has a three-dimensional structure and a total of 22 items. The M-RUQ shows evidence of validity and reliability. Precisely, the factorial structure coming from an exploratory factorial analysis on the first sample (n ¼ 504) was confirmed by a final model of confirmatory factorial analysis (CFA) on a second sample (n ¼ 362). The final CFA model showed adequate goodness of fit, where all the factor loadings showed values higher than .40. Cronbach's a was satisfactory for each domain and for the overall scale. Furthermore, the M-RUQ showed good stability described by the testeretest. Conclusion: The M-RUQ should be used to assess research utilization among nurses for educational or research purposes to address the practice. Further research about its validity and reliability is suggested.
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