Dealloying refers to the partial, selective dissolution of the less noble component(s) of a binary or ternary alloy precursor, resulting in a noble-rich, porous structure that has high surface area. Such surface structure is beneficial for fuel cells (FC) because FC uses platinum (Pt), a scarce metal, to catalyze the oxygen reduction reaction (ORR) at the cathode surface. In order to characterize the benefit of the dealloying process in FC ORR catalysts with the rotating disk electrode (RDE) technique, a high surface area catalyst support, namely 3M Co’s nanostructured thin film (NSTF), was incorporated into the RDE measurements. NSTF-coated glassy carbon (GC) disks were used in RDE experiments on a Pt/Pt1-xIrx (0.05 < x < 0.3) composition spread. ORR measurements using NSTF-coated GC disks measure the catalytic properties with the same morphology, composition and surface structure as would be found in a fuel cell. A series of Pt1-xCox and Pt1-xNix (0.5 < x < 0.8) dealloy catalyst precursor films were tested using NSTF-coated GC disks in RDE studies. The value of x in Pt1-xMx (M = Ni, Co) was selected to be high in order to examine the dealloying process. The catalyst films were examined by a RDE test protocol that tracked the surface enhancement factor (SEF) and ORR current densities over a large number of test cycles. The aim was to measure the catalytic performance of the Pt-M materials as dealloying took place. The SEF of the PtCo and PtNi materials increased rapidly at the beginning and reached a plateau as high as 50 cm2/cm2 while the specific ORR activities increased as the initial M content in the catalyst precursor increased. The impact of the dealloying process on morphology was examined by completely dealloying a Pt3Ni7 precursor, deposited on mirror-polished GC disks, at a constant potential. As the dealloying process continued, the SEF of the material increased from about 1 cm2/cm2 to > 30 cm2/cm2 and resulted in the formation of whisker-like structures.

Title: Nano-structured multicomponent plasma polymers for controlled immobilization of biomolecules Author: Iurii Melnichuk Department / Institute: Department of Macromolecular Physics/Charles University Supervisor of the doctoral thesis: Doc. Ing. Andrey Shukurov, Ph.D. Abstract: The aim of this thesis is to highlight the feasibility of tailored nano- structures in functionalizing surfaces for biointerfacial interactions. Development of new techniques for the production of nanoscaled biomaterials can be of use in a variety of medical and biological applications, e.g. biosensors, microarrays, drug sensors, implants, blood-contacting devices. This thesis first examines the early stages of nano-structured thin film growth fabricated by vapor phase deposition of poly(ethylene). We discuss island growth within a framework of rate equation theory, dynamic scaling theory and capture zone distribution. In a second stage, we test dielectric barrier discharge to activate PE nano-pattern for covalent immobilization of proteins. Finally, we assess cell behavior on surfaces in dependence on morphology and the presence of cell adhesive protein tropoelastin. We employ plasma polymerization to produce ultrathin hydrocarbon layer capable of protein anchoring. The thesis findings for the first time manifest the critical...