Mechanism and kinetics of electrocatalytic reactions

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The purpose of the proposed research is to study electrocatalytic reactions of hydrogen adsorption, absorption and evolution, mechanism and kinetics of metal hydride formation, and modeling of porous electrodes. This study will lead to a better understanding of these reactions and to develop better electrode materials for hydrogen storage and water electrolysis. This research includes:1. Mechanism and kinetics of hydrogen absorption: Our earlier studies suggest that the direct absorption mechanism is the main reaction path and that going through adsorbed hydrogen is much slower. This process will be further studied on other Pt alloys as Pd-Rh, Pd-Ru, etc., which are very important from the electrocatalytic point of view. Adsorption of H and the influence of different poisons on the H absorption processes will be studied. Adsorption isotherms and the kinetics of hydrogen adsorption and absorption will be determined. It should be stressed that several poisons of hydrogen adsorption act as promoters of hydrogen absorption increasing the kinetics of this process. These processes, studied initially in the presence of sulfuric acid will be extended to the non adsorbed perchloric acid and to alkaline solutions.2. Kinetics and thermodynamics of adsorption processes: Hydrogen adsorption reaction is the simplest electrocatalytic reaction. Its kinetics already studied in our laboratory on polycrystalline Pt will be further studied on other noble metals (polycrystalline Rh, Ru, Ir), alloys (Pd-Rh, Pd-Ru, Pd-Ir) and monocrystalline metals using the twin electrode technique developed recently in our lab.3. Modeling of porous electrodes: The kinetics of simple redox reactions will be studied on porous electrodes characterized by the well defined porous geometry (e.g. brush electrodes) to test the theory.