Pd/Ni Synergestic Activity for Hydrogen Oxidation Reaction in Alkaline Conditions

Abstract The investigation of hydrogen oxidation reaction (HOR) in alkaline conditions has been the subject of a wide interest in the past few years with the rise of alkaline membrane fuel cells (AMFCs). In particular, the quest for the lowest content of platinum group metals (PGMs) in the HOR catalyst is ongoing. In this article, we propose the use of a nanoscale Pd layer partially covering a Ni film to provide the most efficient use of the PGM in the HOR catalyst. The Pd/Ni electrodes were prepared by spontaneous and electrolytic deposition of Pd onto smooth polycrystalline Ni surfaces with different surface compositions. The electrodes were characterized by cyclic voltammetry and atomic force microscopy. Electrocatalytic activity in HOR of the Pd/Ni electrodes was measured in alkaline solution by rotating disc electrode method. In the manuscript, we demonstrate that a Pd coverage as low as 1.5% vs. Ni coverage is sufficient to provide a high current density compared to pure Ni. The current density linearly increases with the Pd coverage up to a Pd coverage of 17%; upon further increase in the Pd coverage, the current density reaches a plateau, i.e. the diffusion limit for the HOR process. The comparison with Pd supported on carbon shows the clear benefit for the bimetallic catalyst

Makro-, mikro- és nanoelektrokémia integrációja = Integration of macro, micro and nanoelectrochemistry

A pályázat futamidejének végére létrejött egy pásztázó elektrokémiai mikroszkóp mérőegyüttes, amellyel a mezoszkopikus léptékű felületvizsgálatban elvileg elválasztható a topológiai és a kémiai heterogenitás, a többi felületvizsgálati módszerhez képest egyedülálló módon. A makroszkopikus mérésekben elektrokémiai módszereket, az atomi felbontásúakban pásztázó alagút és atomi erőmikroszkópiát használtunk. A műszeregyüttessel a mezoszkopikus mérettartományban fejlesztés alatt álló szuperkondenzátor-struktúrákat, önszerveződő monorétegeket és lokális korróziós jelenségeket vizsgáltunk. | At the end of the project duration, a scanning electrochemical microscope setup, complete with auxiliary units, was implemented by which one theoretically can distinguish between topological and chemical heterogeneity – a unique possibility as compared to the other surface analysis tools. For the macroscopic measurements electrochemical methods were used while atomic scale measurements were implemented by scanning tunnelling and atomic force microscopy. The setup was used to investigate supercapacitor structures under development, self-organised monolayers and localised corrosion phenomena

Directed deposition of nickel nanoparticles using self-assembled organic template

Self-assembled organic monolayers are useful templates for nanofabrication. Ordered layer of long alkyl-chain molecules can direct the wet chemical deposition of metallic coatings on different substrates. Ordered structures of fatty acids and their motions on the phenyloctane/HOPG interface are observed by scanning tunneling microscopy (STM). Modification of self-assembled fatty acid patterns due to hydroxamic acid presence is also in the focus of the research. Fatty acid layer formation, the structure of the formed thin film on solid/liquid interface, and simultaneous nickel colloidal deposition have been investigated

Zigzag-shaped nickel nanowires via organometallic template-free route

In this manuscript, the formation of nickel nanowires (average size: several tens to hundreds of μm long and 1.0-1.5 μm wide) at low temperature is found to be driven by dewetting of liquid organometallic precursors during spin coating process and by self-assembly of Ni clusters. Elaboration of metallic thin films by low temperature deposition technique makes the preparation process compatible with most of the substrates. The use of iron and cobalt precursor shows that the process could be extended to other metallic systems. In this work, AFM and SEM are used to follow the assembly of Ni clusters into straight or zigzag lines. The formation of zigzag structure is specific to the Ni precursor at appropriate preparation parameters. This template free process allows a control of anisotropic structures with homogeneous sizes and angles on standard Si/SiO2 surface