Article
Chemistry, Physical
A. R. Q. Panesi, R. P. Silva, E. F. Cunha, I. Korkischko, E. I. Santiago
Summary: In this study, a complete non-isothermal model of a HT-PEMFC setup using a PBI/ H3PO4 membrane was developed, modeled, and solved using COMSOL Multiphysics. The model predicted water vapor transport, mass concentration of H3PO4, temperature, and membrane current density distribution. Results showed that phosphoric acid concentration decreases with increasing temperature and relative humidity, while the diffusive flux of water vapor increases with the decrease of the operating voltage.
Article
Chemistry, Physical
A. R. Q. Panesi, R. P. Silva, E. I. Santiago
Summary: A three-dimensional steady-state model was developed to analyze the performance of high-temperature direct ethanol fuel cells (HT-DEFC) based on polybenzimidazole (PBI) electrolytes. The model predicted various distributions and concentrations during operation, and investigated the effects of temperature and humidity on the cell's performance. The study found that PBI properties, H3PO4 lixiviation, and ethanol crossover play significant roles in affecting the HT-DEFC performance.
Article
Polymer Science
Jacqueline A. Maslyn, Louise Frenck, Vijay D. Veeraraghavan, Alexander Muller, Alec S. Ho, Nandan Marwaha, Whitney S. Loo, Dilworth Y. Parkinson, Andrew M. Minor, Nitash P. Balsara
Summary: The study shows that the limiting current density in composite electrolytes increases with the volume fraction of the PEO block. Using the concentrated solution theory enables accurate predictions of limiting current density, with quantitative agreement between experimental measurements and theoretical predictions.
Article
Chemistry, Physical
Rileigh Casebolt DiDomenico, Kelsey Levine, Laila Reimanis, Hector D. Arbuna, Tobias Hanrath
Summary: Electrochemical reduction of CO2 is a promising method to utilize CO2 as a feedstock and store renewable electricity. However, there are gaps in understanding the reaction mechanism and controlling the formation of products. In this study, chronoamperometry is used as a diagnostic tool to gain insights into the complex interplay of electrochemical reactions, chemical reactions, and mass transport. The findings provide important mechanistic implications and information on dominant reaction pathways for CO2 reduction.
Article
Chemistry, Physical
Rileigh Casebolt DiDomenico, Kelsey Levine, Laila Reimanis, Hector D. Abruna, Tobias Hanrath
Summary: The electrochemical reduction of CO2 has the potential to use CO2 as a feedstock for chemical products and as a means to store renewable electricity. However, there are still gaps in our understanding of the reaction mechanism, particularly for the formation of products. In this study, we use time-resolved measurements to gain insights into the complex interactions of electrochemical and chemical reactions in the CO2 reduction process. We hope that this work will inspire further studies to use this method to address outstanding questions in electrochemical CO2 reduction and other multi-step reaction pathways.
Article
Chemistry, Physical
J. O. Leader, Y. Yue, M. R. Walluk, T. A. Trabold
Summary: High-temperature proton exchange membrane fuel cells (HT-PEM) have advantages such as improved fuel impurity tolerance and increased electrode kinetics. This study investigated the voltage degradation of HT-PEM fuel cells operating at 200 degrees C under continuous load conditions and during start-stop cycling. The results showed relatively high degradation rates, but with decreasing average degradation rates over cycles.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Chemistry, Physical
Fang-Fang Cheng, Su-Fang Qin, Le-Xing You, Jian-Jun Sun
Summary: This study presents experimental evidence of the kinetics of hydrogen redox reactions in weak acid solutions. Different redox processes were observed in different solutions, and diffusion coefficients and standard rate constants were estimated.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Fang-Fang Cheng, Su-Fang Qin, Le-Xing You, Jian-Jun Sun
Summary: This study provides a deeper understanding of the kinetics of hydrogen redox reactions, particularly in weak acid solutions, through electrochemical experimental data. The diffusion rates and standard reaction rate constants of the hydrogen redox reactions in different solutions are determined, and multistep and complex reactions are observed in the H8C6O7 solution.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Analytical
Denis Krivic, Nives Vladislavic, Masa Buljac, Ivana Skugor Roncevic, Marijo Buzuk
Summary: The electrochemical behavior of gallic acid on a single-walled carbon nanotubes-modified electrode was investigated using cyclic voltammetry and chronoamperometry. Diffusion phenomena were found to be responsible for the overall current signal, and these phenomena were divided into four processes occurring in thin-layer or solution. The effects of scan rate, gallic acid concentration, and layer thickness on the voltammetric signal were discussed based on the diffusion processes in the thin-layer.
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
(2022)
Article
Electrochemistry
Yurii Yakovlev, Miquel Gamon Rodriguez, Yevheniia Lobko, Maryna Vorokhta, Peter Kus, Iva Matolinova, Vladimir Matolin
Summary: In this study, the gas transport properties of commercially available gas diffusion layers (GDLs) were investigated using a limiting current technique. The average relative diffusivities of oxygen and hydrogen in different GDLs were measured in operating fuel cells. The analysis of oxygen and hydrogen transport provided insights into the gas diffusion performance and water saturation of GDLs at different current densities. It was found that water transport in GDLs is influenced by the GDL thickness. The structural properties of GDLs were also investigated using scanning electron microscopy and mercury intrusion porosimetry techniques. The fuel cell performance of GDLs at different relative humidities was studied and analyzed in relation to their transport and structural properties.
ELECTROCHIMICA ACTA
(2022)
Article
Engineering, Chemical
Funda Arslan, Thomas Bohm, Jochen Kerres, Simon Thiele
Summary: This study demonstrates that confocal Raman microscopy can serve as a non-invasive measurement tool to investigate the status and progress of doping a membrane with phosphoric acid. The doping is shown to be a diffusion-limited process, resulting in a spatially inhomogeneous distribution of phosphoric acid unless doping is performed to saturation.
JOURNAL OF MEMBRANE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Yasinalli Tamboli, Bharat B. Kashid, Ram Prasad Yadav, Mohammad Rafeeq, Ravindra Yeole, Arvind Y. Merwade
Summary: A large-scale, chromatography-free process has been developed to eliminate triphenylphosphine oxide (TPPO) from the crude product of Mitsunobu and Wittig reactions. The divergence in physicochemical properties between TPPO and the product was harnessed to precipitate TPPO directly from the reaction mixture, resulting in high purity of the final product through simple filtration at a pilot plant.
Article
Nanoscience & Nanotechnology
Joseph Jang, Do-Hyung Kim, Byeol Kang, Joo-Hyoung Lee, Chanho Pak, Jae-Suk Lee
Summary: The influence of N-substituent and pK(a) of azole rings on the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) was investigated. Experimental comparisons of membranes with four different azole substituents showed that methyl-substituted azole membranes had higher phosphoric acid doping levels, while unsubstituted azole membranes more effectively improved proton conductivity.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Physical
Ke Shan, Zhongzhou Yi, Jing Wang
Summary: A novel dense diffusion barrier material was prepared using a sol-gel method, showing excellent crystal structure and electrical conductivity. The Y-doping amount significantly affected the electrical conductivity and sinterability of the material. The limiting current oxygen sensor based on the dense diffusion barrier material showed excellent sensing performance.
Article
Mathematics, Applied
Stephan Daniel Schwoebel, Markus Mueller, Thomas Mehner, Thomas Lampke
Summary: The limiting current density is a crucial indicator in electroplating, representing the maximum current density at which a metal can be effectively deposited from an electrolyte. This article presents a simple model for computing the limiting current density based on diffusion-reaction equations in one spatial dimension. The model, although making various assumptions, is particularly useful for screening and comparative work and can be easily adjusted to experimental measurements.