Atomic Hydrogen as a Reducing Agent

Bergh, A. A.

doi:10.1002/j.1538-7305.1965.tb01661.x

Cited by 31 publications

(9 citation statements)

References 25 publications

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“…However, it is well known that H is more active than H 2 , as it can reduce metal oxides such as CuO at room temperature. 49 The poor activity of H 2 as a reducing agent compared with that of H is further confirmed here, following Li et al, 26 /Ti = −1.63 V). However the results obtained here were not so; metallic Sn, Co, and Ni were not produced in their solutions.…”

Section: Morphologies and Compositions Of The Ti-aunps Modifiedsupporting

confidence: 84%

Activation of Titanium for Synthesis of Supported and Unsupported Metallic Nanoparticles

Amin

Fadlallah

Alosaimi

2014

J. Electrochem. Soc.

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Titanium (Ti) resists corrosion due to spontaneous passivation and subsequent formation of a stable, substantially inert oxide film. This passive film limits the reducing ability of Ti in wet chemical synthesis. Aggressive anions are applied here to destabilize Ti passivity, with the objective of activating Ti as a reducing agent for wet-chemical synthesis, through the formation of unsupported and supported metallic nanoparticles (MNPs). For instance, within the first minute of Ti immersion in a standard gold solution (SGS), 1000 ± 3 μg Au/mL in 2% HCl, gold nanoparticles (AuNPs) in solution (unsupported) and a considerable population of highly dispersed AuNPs on Ti (Ti-supported AuNPs) are obtained. This occurs at room temperature, without using reducing agents, stabilizers, or any chemical pre-treatments. Electrochemical measurements revealed that the passivity of Ti was destabilized (oxide thinning/dissolution) in the SGS. The addition of F − to the SGS promoted destabilization of the passive film, and hence activated the reducing ability of Ti. This in turn resulted in significant increase in the population of AuNPs on Ti. Reduction of cations in solution by the active nascent (atomic) hydrogen (H) generated by substrate (Ti) dissolution, promoted by the addition of F − , in acidic medium is confirmed here and discussed vs. conductivity of the oxide (passive) film and solution pH. Experimental findings reveal that the relevance of H as the actual reducing agent is limited to instantaneous and non-conductive passive films. Solution pH studies on such passive films show that the Nernst equation (dE H/H + /d(pH) = −0.059 V) controls the wet chemical synthesis of MNPs rather than E o reduction of the base metal (the substrate). Based on polarization measurements, the prepared Ti-supported AuNPs are demonstrated here as highly active electrocatalysts (better than Pt) for the hydrogen evolution reaction (HER) in 0.1 M HCl solution.Nanoparticles constitute a key area of research and development in the burgeoning field of nanotechnology. The attraction of nanoparticles lies in the myriad of attractive characteristics which can be achieved by reducing suitable materials from the bulk to the nanometer size, these characteristics ranging from increased surface/volume ratio to novel quantum confinement effects. 1 Examples of property enhancements include magnetic, optical, biosensing, thermoelectric, semiconducting, catalytic, energy storage and thermal properties. 2-7 An interesting aspect of nanoparticles is the wide range of material classes in which nanoparticles are useful, including semiconductor, dielectric, metallic, ceramic, composite and polymer nanoparticles. For these reasons, metal nanoparticles have attracted a high interest in scientific research and industrial applications. [8][9][10] Metal nanoparticles (MNPs) can be produced by reducing metal salts with reducing agents and stabilizing them with capping ligands, 11 and they can be subsequently attached to another metal. However, it is more desirable to d...

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Section: Morphologies and Compositions Of The Ti-aunps Modifiedsupporting

confidence: 84%

Activation of Titanium for Synthesis of Supported and Unsupported Metallic Nanoparticles

Amin

Fadlallah

Alosaimi

2014

J. Electrochem. Soc.

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“…An obvious explanation for this is the formation of water from silicates under bombardment of excited hydrogen atoms. Evidence for this has been reported before in this laboratory (I), and by other workers (11,12).…”

Section: Nature Of the Surfacesupporting

confidence: 80%

Studies on hydrogen–oxygen systems in the electrical discharge. III. Surface effects

Brunet¹,

Deglise²,

Giguère³

1970

Can. J. Chem.

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Surface effects in the reactions of dissociated hydrogen–oxygen systems and the products condensed therefrom have been investigated. Water vapor at about 0.1 Torr was streamed at high velocity through an electrodeless discharge confined in tubes of different materials or with various surface coatings. In all cases the products trapped in liquid nitrogen evolved oxygen gas on warming, but the relative amounts varied considerably from one type of surface to another. In some cases there was clear evidence that the walls of discharge tube were attacked by hydrogen atom bombardment. The decomposition, both thermal and electrical, of pure hydrogen peroxide vapor was studied likewise. The pyrolysis products gave off very little oxygen on warming. By contrast the products from electrical decomposition, even at low power level, evolved much oxygen, most of it above the melting point.It is concluded that there is always some decomposition of hydrogen peroxide in the trapped products. However, this does not seem sufficient to account for all the evolved oxygen; at least not in the case of dissociated water vapor.

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“…A controlled experiment with the passage of H 2 gas overnight reveals that H 2 cannot reduce an aqueous solution of Na 2 PdCl 4 . In contrast, H is more active than H 2 and it can reduce metal oxides such as CuO at room temperature21. As mentioned above, Pd particles can form on the Al foil in the early stage of pitting corrosion, when the oxide film is not broken.…”

Section: Resultsmentioning

confidence: 99%

“…The H is produced as an intermediate of the pitting corrosion of Al below the oxide film20. It cannot reduce aluminum oxide21 because of the very low standard reduction potential of E° Al(OH) 3 /Al = −2.31 V, but it can diffuse through to the top of the oxide film22. The hydrogen electro-oxidation reaction continues on the top of the oxide film and the released electrons flow onto the surface of the formed Pd particles for further reduction of [PdCl x (OH) y ] 2− , leading to the growth of the Pd particles.…”

Section: Resultsmentioning

confidence: 99%

Activation of Aluminum as an Effective Reducing Agent by Pitting Corrosion for Wet-chemical Synthesis

Cochell

Manthiram

2013

Sci Rep

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Metallic aluminum (Al) is of interest as a reducing agent because of its low standard reduction potential. However, its surface is invariably covered with a dense aluminum oxide film, which prevents its effective use as a reducing agent in wet-chemical synthesis. Pitting corrosion, known as an undesired reaction destroying Al and is enhanced by anions such as F−, Cl−, and Br− in aqueous solutions, is applied here for the first time to activate Al as a reducing agent for wet-chemical synthesis of a diverse array of metals and alloys. Specifically, we demonstrate the synthesis of highly dispersed palladium nanoparticles on carbon black with stabilizers and the intermetallic Cu2Sb/C, which are promising candidates, respectively, for fuel cell catalysts and lithium-ion battery anodes. Atomic hydrogen, an intermediate during the pitting corrosion of Al in protonic solvents (e.g., water and ethylene glycol), is validated as the actual reducing agent.

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Atomic Hydrogen as a Reducing Agent

Cited by 31 publications

References 25 publications

Activation of Titanium for Synthesis of Supported and Unsupported Metallic Nanoparticles

Activation of Titanium for Synthesis of Supported and Unsupported Metallic Nanoparticles

Studies on hydrogen–oxygen systems in the electrical discharge. III. Surface effects

Activation of Aluminum as an Effective Reducing Agent by Pitting Corrosion for Wet-chemical Synthesis

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