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    Evaluation of hydrogen storage performance of ZrTiVNiCrFe in electrochemical and gas-solid reactions
    (Pergamon-Elsevier Science Ltd, 2020) Zadorozhnyy, V; Sarac, B.; Berdonosova, E.; Karazehir, T.; Lassnig, A.; Gammer, C.; Zadorozhnyy, M.
    In the present study, the hydrogen storage performance of multi-principal-component ZrTiVNiCrFe alloy produced through rapid solidification has been examined by electro-chemical methods and gas-solid reactions. XRD and EBSD analyses reveal the hexagonal Laves phase structure (type C14) with average grain size of 300 nm and root-mean-square microstrain of 0.19%. Cyclic voltammetry and electrochemical impedance spectroscopy analyses in the hydrogen sorption/desorption region give insight to the sorption/desorption kinetics and the change in the desorption charge in terms of the applied potential. The pressure-composition isotherms measured in course of gas-solid reaction confirm the hydrogen storage capacity reaching 1.6 wt% at the first hydrogenation at room temperature, then reducing to 1.3-1.4% during subsequent cycling. According to the calorimetric titration study, there is a significant hysteresis primarily caused by the non-equilibrium character of the hydrogenation process. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Porosity and thickness effect of Pd-Cu-Si metallic glasses on electrocatalytic hydrogen production and storage
    (Elsevier Sci Ltd, 2021) Sarac, B.; Karazehir, T.; Yuece, E.; Muehlbacher, M.; Sarac, A. S.; Eckert, J.
    This contribution places emphasis on tuning pore architecture and film thickness of mesoporous Pd-Cu- Si thin films sputtered on Si/SiO2 substrates for enhanced electrocatalytic and hydrogen sorption/desorp-tion activity and their comparison with the state-of-the-art thin film electrocatalysts. Small Tafel slope of 43 mV dec-1 for 1250 nm thick coating on 2 gm diameter pores with 4.2 gm interspacing electrocatalyst with comparable hydrogen overpotentials to the literature suggests its use for standard fuel cells. The lar-gest hydrogen sorption has been attained for the 250 nm thick electrocatalyst on 5 gm pore diameter with 12 gm interspacing (2189 gC cm-2 per CV cycle), making it possible for rapid storage systems. Moreover, the charge transfer resistance described by an equivalent circuit model has an excellent cor-relation with Tafel slopes. Along with its very low Tafel slope of 42 mV dec-1 10 nm thick electrocatalyst on 2 gm diameter pores with 4.2 gm interspacing has the highest capacitive response of ti 0.001 S sn cm-2 and is promising to be used as a nano-charger and hydrogen sensor. The findings of Si/SiO2 supported mesoporous Pd-based metallic glass (MG) assemblies suggest a similar design applicability for crystalline systems and other MG types. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).