scholarly journals Electrocatalytic Activity of Galvanostatically Deposited Ni thin Films for Methanol Electrooxidation

2019 ◽  
Author(s):  
Maria Paula Salinas-Quezada ◽  
D. Alfonso Crespo-Yapur ◽  
Abraham Cano-Marquez ◽  
Marcelo Videa
Keyword(s):  
Electrocatalytic Activity ◽  
Noble Metals ◽  
Supporting Electrolyte ◽  
Surface Concentration ◽  
Thin Layers ◽  
Synthetic Methods ◽  
Constant Current ◽  
Direct Alcohol Fuel Cells ◽  
Oxidation Of Methanol ◽  
Polycrystalline Gold

Nickel and nickel-based nanomaterials are an attractive choice to replace noble metals as electrocatalyst in alkaline direct alcohol fuel cells (DAFCs) owing to their lower cost and suitable electrocatalytic activity. Among the different synthetic methods available for the production of nanostructured materials, galvanostatic electrodeposition offers a fast and simple means of fabricating active electrodes. Therefore, thin-layers of nickel were electrodeposited onto polycrystalline gold electrodes using constant current pulses from an electrolyte containing 50 mM NiSO4. The electrocatalytic properties of the nickel nanostructures in alkaline medium, in which the catalytic species NiOOH is formed, were evaluated through cyclic voltammetry in 0.5 M methanol + 1 M KOH. The effects of current density pulse and the presence of sulfate or chloride anions in the supporting electrolyte on the electrocatalytic activity of the deposits were studied using Ni(OH)2 surface concentration, Gamma, and electrocatalytic intensity, EI, as performance parameters. It was found that highest electrolcatalytic activities were obtained when using current densities pulses close to 4.0 mA/cm2 in the presence of sulfates. It was found that the presence of sulfates leads to a strong correlation between the electrocatalytic activity for the oxidation of methanol and the surface concentration of Ni(OH)2.

EXPRESS: Spectral Considerations for Standoff Infrared Detection of RDX on Reflective Aluminum

2021 ◽  
pp. 000370282110538
Author(s):  
Kevin J Major ◽  
Jas Sanghera ◽  
Mikella E. Farrell ◽  
Ellen L Holthoff ◽  
Paul M Pellegrino ◽  
...  
Keyword(s):  
Surface Concentration ◽  
Thin Layers ◽  
Infrared Detection ◽  
Aluminum Surface ◽  
Material System ◽  
Spectral Signatures ◽  
Spectral Changes ◽  
Standoff Detection ◽  
Infrared Spectrometer ◽  
Specific Material

This paper examines infrared spectroscopic effects for the standoff detection of an explosive material, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), inkjet printed on an aluminum surface. Results of a spectroscopic study are described, using multiple optical setups. These setups were selected to explore how variations in the angles of incidence and collection from the surface of the material result in corresponding variations in the spectral signatures. The goal of these studies is to provide an understanding of these spectral changes, since it affects standoff detection of hazardous materials on a reflective substrate. We demonstrate that variations in spectral effects are dependent on the relative surface concentration of the deposited RDX. We also show that it is reasonable to use spectroscopic data collected in a standard laboratory infrared spectrometer outfitted with a variable angle reflectometer set at 0 as reference spectra for data collected in a standoff configuration. These results are important to provide a systematic approach to understanding IR spectra collection using standoff systems in the field, and to allow for comparison between such data, and data collected in the laboratory. Though the precise results are constrained to a specific material system (thin layers on a reflective substrate), the approach and general discussion provided are applicable to a broad range of IR standoff sensing techniques and applications.

scholarly journals Specific-Ion Effects Directed Noble Metal Aerogels: Versatile Manipulation for Electrocatalysis and Beyond

2019 ◽  
Author(s):  
RAN DU ◽  
YUE HU ◽  
René Hübner ◽  
Jan-Ole Joswig ◽  
Xuelin Fan ◽  
...  
Keyword(s):  
Porous Materials ◽  
Noble Metal ◽  
Noble Metals ◽  
Sol Gel ◽  
Synthetic Methods ◽  
Superior Performance ◽  
Gelation Mechanism ◽  
Practical Applications ◽  
Specific Ion Effects ◽  
Ion Effects

<div>Noble metal foams (NMFs) are a new class of functional porous materials featuring properties of both noble metals and monolithic porous materials, providing impressive prospects in catalysis, bio-sensing, plasmonic technologies, etc...Among reported synthetic methods to date, the sol-gel approach manifests overwhelming advantages for versatile synthesis of controlled nanostructured NMFs under mild condition. However, limited gelation methods and insufficient understanding of the underlying mechanism retards structure/composition manipulation of NMFs, hampering ondemand designing for practical applications. Herein highly tunable NMFs are fabricated at room temperature by activating specific-ion effects and regulating ion-nanoparticle interactions, affording various single/alloy NMFs with adjustable compositions (Au, Ag, Pd, Pt), ligament sizes (3.1~142.0 nm), and special morphologies. Their superior performance in programmable self-propulsion devices and electrocatalytic alcohol oxidation are demonstrated. This study provides not only a conceptually new route to fabricate and manipulate functional NMFs, but also an overall picture in understanding the gelation mechanism. It may pave the way for on-target designing versatile NMFs for various applications.</div>

Morphology controlled surface sulfurized CoMn2O4 microspikes electrocatalyst for water splitting with excellent OER rate for binder-free electrocatalytic oxygen evolution

2021 ◽  
Author(s):  
Ali Bahadur ◽  
Waseem Hussain ◽  
Shahid Iqbal ◽  
Farman Ullah ◽  
Muhammad Shoaib ◽  
...  
Keyword(s):  
Transition Metal ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Electrocatalytic Activity ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Binder Free ◽  
Synthesis Routes

Transition metal mixed oxides have drawn extensive interest as oxygen evolution electrocatalysts alternatives to noble metals-based material but generally involve prolonged synthesis routes and limited electrocatalytic activity and stability. Herein...

The electrocatalytic hydrogenation of fused poly cyclic aromatic compounds at Raney nickel electrodes: the influence of catalyst activation and electrolysis conditions

1990 ◽  
Vol 68 (7) ◽  
pp. 1218-1227 ◽  
Author(s):  
Denis Robin ◽  
Michel Comtois ◽  
Anna Martel ◽  
René Lemieux ◽  
Amoy Kam Cheong ◽  
...  
Keyword(s):  
Raney Nickel ◽  
Supporting Electrolyte ◽  
Aqueous Sodium Hydroxide ◽  
Constant Current ◽  
Electrocatalytic Hydrogenation ◽  
Catalyst Activation ◽  
Nickel Electrodes ◽  
Initial Ph ◽  
Raney Ni ◽  
Tetrabutylammonium Chloride

The electrocatalytic hydrogenation (ECH) of phenanthrene, anthracene, and naphthalene has been investigated under constant current at Raney nickel electrodes in a mixed aqueous organic medium. The influence of various parameters on the efficiency of the process determined by the current efficiency (a measure of the competition between hydrogenation and hydrogen evolution, the only two electrochemical processes occurring), the extent of hydrogenation (yield of octahydro-derivatives), and the conversion rate was studied with phenanthrene. The best conditions were ethylene glycol or propylene glycol as cosolvent containing between 1.5 to 5% of water, a neutral or slightly acidic medium containing boric acid (0.1 M) as buffer (initial pH of 2.6, final pH of 6.0–6.2), sodium chloride or tetrabutylammonium chloride as supporting electrolyte, a temperature of 80° C, and a current density of 42 to 84 mA/cm2. The most active electrodes (consisting of Raney Ni particles dispersed in a nickel matrix and surrounded by a layer of porous nickel) were obtained by leaching the dispersed alloy particles at 75 °C for 7 h in 30% aqueous sodium hydroxide. The electrohydrogenation stopped at derivatives with a single aromatic ring, namely the octahydrophenanthrenes, octahydroanthracenes, and tetralin. In a non-buffered medium, tetrahydrophenanthrene could be obtained with selectivities of 80% or better. Keywords: electrocatalytic hydrogenation, Raney nickel electrodes, phenanthrene, anthracene, naphthalene.

scholarly journals Specific ion effects directed noble metal aerogels: Versatile manipulation for electrocatalysis and beyond

2019 ◽  
Vol 5 (5) ◽  
pp. eaaw4590 ◽  
Author(s):  
Ran Du ◽  
Yue Hu ◽  
René Hübner ◽  
Jan-Ole Joswig ◽  
Xuelin Fan ◽  
...  
Keyword(s):  
Noble Metal ◽  
Noble Metals ◽  
Sol Gel ◽  
Functional Materials ◽  
Synthetic Methods ◽  
Superior Performance ◽  
Formation Mechanisms ◽  
Gelation Mechanism ◽  
Specific Ion Effects ◽  
Ion Effects

Noble metal foams (NMFs) are a new class of functional materials featuring properties of both noble metals and monolithic porous materials, providing impressive prospects in diverse fields. Among reported synthetic methods, the sol-gel approach manifests overwhelming advantages for versatile synthesis of nanostructured NMFs (i.e., noble metal aerogels) under mild conditions. However, limited gelation methods and elusive formation mechanisms retard structure/composition manipulation, hampering on-demand design for practical applications. Here, highly tunable NMFs are fabricated by activating specific ion effects, enabling various single/alloy aerogels with adjustable composition (Au, Ag, Pd, and Pt), ligament sizes (3.1 to 142.0 nm), and special morphologies. Their superior performance in programmable self-propulsion devices and electrocatalytic alcohol oxidation is also demonstrated. This study provides a conceptually new approach to fabricate and manipulate NMFs and an overall framework for understanding the gelation mechanism, paving the way for on-target design of NMFs and investigating structure-performance relationships for versatile applications.

scholarly journals Porous SnO2 hexagonal prism-attached Pd/rGO with enhanced electrocatalytic activity for methanol oxidation

RSC Advances ◽  
2017 ◽  
Vol 7 (47) ◽  
pp. 29909-29915 ◽  
Author(s):  
Yiran Hu ◽  
Tao Mei ◽  
Jinhua Li ◽  
Jianying Wang ◽  
Xianbao Wang
Keyword(s):  
Methanol Oxidation ◽  
Electrocatalytic Activity ◽  
Hexagonal Prism ◽  
Catalytic Activities ◽  
Oxidation Of Methanol

Herein, we chose porous SnO2 hexagonal prisms as a new promoter for Pd/rGO electrocatalyst. The as-prepared catalyst exhibited excellent electrochemical catalytic activities and enhanced durability for the oxidation of methanol.

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