Increasing the amount of hydrogen that is electrochemically inserted into materials is important for studying superconductivity and hydrogen embrittlement, and improving hydrogen storage capabilities. Surfaces can be engineered to accomplish this task with better insight into how the composition of a material's first few atomic layers affects the electrochemical insertion of hydrogen.
The goal of this work was to gain a better understanding of how the addition of surface metals affects the amount of electrochemically inserted hydrogen in materials so that surfaces can be engineered to maximize the insertion.
In the first phase of the experiments, we studied the effect of Pb surface concentration on the amount of electrochemically stored hydrogen in Pd cathodes (PdHx). To this end, different amounts of Pb were added to the 0.1 M LiOH electrolyte to be deposited onto Pd cathodes during galvanostatic experiments. The investigated amount of added Pb was between 1 μg cm−2 and 23 μg cm−2 with respect to the geometric area of the Pd cathode. We provide analysis on the cause of this optimum amount which suggests the Pb is affecting the Volmer, Heyrovsky, and Tafel reaction rates. Specifically, analysis of the Tafel reaction suggested the maximum x at a given working potential (-0.5 V vs RHE) correlated with the amount of Pb that resulted in the lowest joT.
In the second phase, we used DFT calculations as a first step in screening materials to study. Then, we studied the effect of different surfaces consisting of Pb, Bi, and Pt on the amount of stored hydrogen. Finally, we provided analysis of the Volmer and Tafel reaction rates. The result of the analysis shows the highest amount of stored hydrogen under given working conditions is found when combining a material that inhibits the Tafel reaction, joT (e.g. Bi), with a material that facilitates the Volmer reaction, joV (e.g. Pt).
The goal of this work was to gain a better understanding of how the addition of surface metals affects the amount of electrochemically inserted hydrogen in materials so that surfaces can be engineered to maximize the insertion.
In the first phase of the experiments, we studied the effect of Pb surface concentration on the amount of electrochemically stored hydrogen in Pd cathodes (PdHx). To this end, different amounts of Pb were added to the 0.1 M LiOH electrolyte to be deposited onto Pd cathodes during galvanostatic experiments. The investigated amount of added Pb was between 1 μg cm−2 and 23 μg cm−2 with respect to the geometric area of the Pd cathode. We provide analysis on the cause of this optimum amount which suggests the Pb is affecting the Volmer, Heyrovsky, and Tafel reaction rates. Specifically, analysis of the Tafel reaction suggested the maximum x at a given working potential (-0.5 V vs RHE) correlated with the amount of Pb that resulted in the lowest joT.
In the second phase, we used DFT calculations as a first step in screening materials to study. Then, we studied the effect of different surfaces consisting of Pb, Bi, and Pt on the amount of stored hydrogen. Finally, we provided analysis of the Volmer and Tafel reaction rates. The result of the analysis shows the highest amount of stored hydrogen under given working conditions is found when combining a material that inhibits the Tafel reaction, joT (e.g. Bi), with a material that facilitates the Volmer reaction, joV (e.g. Pt).
Documents and presentations
S. Hamm, D. Knies, O.Dmitriyeva, R. Cantwell, M. McConnell "Optimal Surface Doping of Lead for Increased Electrochemical Insertion of Hydrogen into Palladium", Electrochimica Acta, v. 233, 10 April 2017, Pages 71–77
S.C. Hamm, O. Dmitriyeva, D.L. Knies, R. Cantwell, M. McConnell, Engineering Palladium Surfaces to Enhance the Electrochemical Storage of Hydrogen, in: ECS Trans., 2017: pp. 65–79, doi:10.1149/07711.0065ecst
S.C. Hamm, O. Dmitriyeva, D.L. Knies, R. Cantwell, M. McConnell, Engineering Palladium Surfaces to Enhance the Electrochemical Storage of Hydrogen, in: ECS Trans., 2017: pp. 65–79, doi:10.1149/07711.0065ecst
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