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

Degradation Effects at the Porous Transport Layer/Catalyst Layer Interface in Polymer Electrolyte Membrane Water Electrolyzer

The porous transport layer (PTL)/catalyst layer (CL) interface plays a crucial role in the achievement of high performance and efficiency in polymer electrolyte membrane water electrolyzers (PEMWEs). This study investigated the effects of the PTL/CL interface on the degradation of membrane electrode assemblies (MEAs) during a 4000 h test, comparing the MEAs assembled with uncoated and Ir-coated Ti PTLs. Our results show that compared to an uncoated PTL/CL interface, an optimized interface formed when using a platinum group metal (PGM) coating, i.e., an iridium layer at the PTL/CL interface, and reduced the degradation of the MEA. The agglomeration and formation of voids and cracks could be found for both MEAs after the long-term test, but the incorporation of an Ir coating on the PTL did not affect the morphology change or oxidation of IrOx in the catalyst layer. In addition, our studies suggest that the ionomer loss and restructuring of the anodic MEA can also be reduced by Ir coating of the PTL/CL interface. Optimization of the PTL/CL interface improves the performance and durability of a PEMWE

Performance and 4,000 Hours Durability Behavior of Noble Metal-Coated Porous Transport Layers for PEM Walter Electrolyzers

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Iridium nanoparticles for the oxygen evolution reaction: Correlation of structure and activity of benchmark catalyst systems

The rotating disk electrode (RDE) is a well-known and established electrochemical tool for evaluating typical powdery electrocatalyst platforms such as platinum supported on carbon black. Unfortunately, the same cannot be said of the iridium-based catalysts typically used in polymer electrolyte membrane (PEM) water electrolyzers. The challenge essentially relies on three aspects: a) high anodic overpotentials which fatally destroy any electrode substrate; b) low loading RDE-inks for catalyst screenings may show strong sedimentation c) iridium does not show defined peaks during cyclic voltammetry. With this work, a newly developed method is presented which allows the characterization of the electrocatalytic properties of iridium based electrocatalysts in a true RDE configuration. Here we aimed to access the electrochemistry of various commercial iridium-based catalysts with different structures. We show that the stability of glassy carbon RDE and of carbon black, added to the ink in order to stabilize the dispersion is sufficient during the electrochemical testing protocol used. Reproducibility of activity results obtained on various samples is increased by stabilizing the dispersions with carbon black, resulting in reproducible and homogeneous catalyst thin films

Multi-Component Ni-Ir Electrocatalysts toward Efficient Oxygen Evolution Reaction

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