The Experts below are selected from a list of 7971 Experts worldwide ranked by ideXlab platform
Thomas Bligaard - One of the best experts on this subject based on the ideXlab platform.
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Nickel Silver alloy electrocatalysts for hydrogen evolution and oxidation in an alkaline electrolyte
Physical Chemistry Chemical Physics, 2014Co-Authors: Maureen H Tang, Christopher Hahn, Aidan J Klobuchar, Jia Wei Desmond Ng, Jess Wellendorff, Thomas BligaardAbstract:The development of improved catalysts for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in basic electrolytes remains a major technical obstacle to improved fuel cells, water electrolyzers, and other devices for electrochemical energy storage and conversion. Based on the free energy of adsorbed hydrogen intermediates, theory predicts that alloys of Nickel and Silver are active for these reactions. In this work, we synthesize binary Nickel–Silver bulk alloys across a range of compositions and show that Nickel–Silver alloys are indeed more active than pure Nickel for hydrogen evolution and, possibly, hydrogen oxidation. To overcome the mutual insolubility of Silver and Nickel, we employ electron-beam physical vapor codeposition, a low-temperature synthetic route to metastable alloys. This method also produces flat and uniform films that facilitate the measurement of intrinsic catalytic activity with minimal variations in the surface area, ohmic contact, and pore transport. Rotating-disk-electrode measurements demonstrate that the hydrogen evolution activity per geometric area of the most active catalyst in this study, Ni0.75Ag0.25, is approximately twice that of pure Nickel and has comparable stability and hydrogen oxidation activity. Our experimental results are supported by density functional theory calculations, which show that bulk alloying of Ni and Ag creates a variety of adsorption sites, some of which have near-optimal hydrogen binding energy.
Richard G Compton - One of the best experts on this subject based on the ideXlab platform.
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magnetically moveable bimetallic Nickel Silver nanoparticle carbon nanotube composites for methanol oxidation
New Journal of Chemistry, 2009Co-Authors: Ronan Baron, Neil V Rees, Lei Xiao, Richard G ComptonAbstract:Multi-walled carbon nanotubes (CNTs) functionalized both by Nickel and Silver nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The new composite material was characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The electroactivity of the bi-functionalized CNTs multi-walled carbon nanotubes was assessed in respect to the electrooxidation of methanol. It was found that the carbon nanotube supported Silver nanoparticles have significantly higher catalytic properties than the bulk metal of the same surface area. Furthermore, it was shown that the presence of only a very small proportion of magnetic Nickel nanoparticles (1.5% of the total number of metallic nanoparticles) allows the bi-functionalized carbon nanotubes to be moved magnetically in solution, making them easily recoverable after use whilst keeping an optimal electrocatalytic surface area.
Mark T Swihart - One of the best experts on this subject based on the ideXlab platform.
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flame synthesized Nickel Silver nanoparticle inks provide high conductivity without sintering
Chemical Engineering Journal, 2019Co-Authors: Mohammad Moein Mohammadi, Santosh Srivatsa Gunturi, Shikuan Shao, Shailesh Konda, Raymond D Buchner, Mark T SwihartAbstract:Abstract A new concept for the synthesis of conductive metal nanoparticle inks (nano-inks) is introduced using a one-step continuous flame-based process. Bimetallic Nickel (Ni)-Silver (Ag) nanopowders are simultaneously produced and functionalized in a High Temperature Reducing Jet (HTRJ) reactor. The HTRJ process allows rapid aerosol (gas phase) formation of multicomponent metal nanoparticles with relatively high production rates from low-cost metal precursors. Octylamine, a volatile aliphatic amine, is sprayed into the reactor effluent after the particle formation zone to cap nanoparticles as they form. Ni-Ag Functionalized Nano Powders (FNPs) were characterized and compared with Bare Nano Powders (BNPs) to verify that in situ ligand attachment was successful. Nano-inks were prepared by dispersing FNPs in an organic solvent. Conductive films were fabricated using different nano-ink compositions starting from pure Ni to 50 wt% Ni. With the use of a small capping agent, films containing 50 wt% (65 at%) Ni provide an electrical conductivity of 5.14 × 104 S m−1 without any post-processing. Conductivity increased to 4.22 × 105 S m−1 after thermal annealing in an inert environment. These sintering-free bimetallic conductive nanoparticles can be used as a lower cost replacement for current Silver inks for single-step printing of conductive traces without post-processing.
Ronan Baron - One of the best experts on this subject based on the ideXlab platform.
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magnetically moveable bimetallic Nickel Silver nanoparticle carbon nanotube composites for methanol oxidation
New Journal of Chemistry, 2009Co-Authors: Ronan Baron, Neil V Rees, Lei Xiao, Richard G ComptonAbstract:Multi-walled carbon nanotubes (CNTs) functionalized both by Nickel and Silver nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The new composite material was characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The electroactivity of the bi-functionalized CNTs multi-walled carbon nanotubes was assessed in respect to the electrooxidation of methanol. It was found that the carbon nanotube supported Silver nanoparticles have significantly higher catalytic properties than the bulk metal of the same surface area. Furthermore, it was shown that the presence of only a very small proportion of magnetic Nickel nanoparticles (1.5% of the total number of metallic nanoparticles) allows the bi-functionalized carbon nanotubes to be moved magnetically in solution, making them easily recoverable after use whilst keeping an optimal electrocatalytic surface area.
Jess Wellendorff - One of the best experts on this subject based on the ideXlab platform.
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Nickel Silver alloy electrocatalysts for hydrogen evolution and oxidation in an alkaline electrolyte
Physical Chemistry Chemical Physics, 2014Co-Authors: Maureen H Tang, Christopher Hahn, Aidan J Klobuchar, Jia Wei Desmond Ng, Jess Wellendorff, Thomas BligaardAbstract:The development of improved catalysts for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in basic electrolytes remains a major technical obstacle to improved fuel cells, water electrolyzers, and other devices for electrochemical energy storage and conversion. Based on the free energy of adsorbed hydrogen intermediates, theory predicts that alloys of Nickel and Silver are active for these reactions. In this work, we synthesize binary Nickel–Silver bulk alloys across a range of compositions and show that Nickel–Silver alloys are indeed more active than pure Nickel for hydrogen evolution and, possibly, hydrogen oxidation. To overcome the mutual insolubility of Silver and Nickel, we employ electron-beam physical vapor codeposition, a low-temperature synthetic route to metastable alloys. This method also produces flat and uniform films that facilitate the measurement of intrinsic catalytic activity with minimal variations in the surface area, ohmic contact, and pore transport. Rotating-disk-electrode measurements demonstrate that the hydrogen evolution activity per geometric area of the most active catalyst in this study, Ni0.75Ag0.25, is approximately twice that of pure Nickel and has comparable stability and hydrogen oxidation activity. Our experimental results are supported by density functional theory calculations, which show that bulk alloying of Ni and Ag creates a variety of adsorption sites, some of which have near-optimal hydrogen binding energy.