Auto-inhibition of hydrogen gas evolution on gold in aqueous acid solution

Burke, Declan; O’Mullane, Anthony P.; Lodge, Vincent E.; Mooney, M.

doi:10.1007/s100080000153

Cited by 34 publications

(24 citation statements)

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“…The basic principle in such superactivation pretreatment is to insert energy into (or do work on) the sample, or the outer layers of same, in such a manner that after pretreatment some of the inserted energy remains trapped in the sample in the form of MMS states. The superactivation pretreatments (which tend to be severe) used for gold include rapid thermal quenching (31,32) and prolonged cathodization (33,34) (the latter induces hydrogen embrittlement of the metal surface). Rapid thermal quenching is a standard procedure used commercially to produce metastable metals (35).…”

Section: The Electrochemistry Of Mms Goldmentioning

confidence: 99%

Scope for new applications for gold arising from the electrocatalytic behaviour of its metastable surface states

2004

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The electrocatalytic behaviour of gold in aqueous media is surprisingly complex and a novel view of gold electrode surfaces is proposed to explain the observed electrochemical responses. The metal surface is considered as a chemically (or redox) modified electrode, with equilibrated, low energy, surface gold atoms functioning as a relatively inert support and low coverage, high energy, protruding gold atoms (or minute clusters of same) functioning as electrocatalytic redox mediators. The protruding atoms are viewed as surface active sites and the complex electrocatalytic behaviour is attributed to the basic instability of the mediators, the diversity (and poor control) of same, and the acid/base (or hydrolysis) behaviour of the oxidized states of the mediators. It is assumed that major advances in the application of gold in the heterogeneous catalysis of gas phase reactions will be accompanied by similar advances in the use of gold in the electrocatalysis area; however, this will require considerable work of both a practical and theoretical nature.

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Section: The Electrochemistry Of Mms Goldmentioning

confidence: 99%

Scope for new applications for gold arising from the electrocatalytic behaviour of its metastable surface states

2004

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“…If the metal surface is disturbed or activated, eg by severe cathodization (which results in (25,26) hydrogen embrittlement) or severe thermal pretreatment (8), gold atoms (or clusters of same) become poorly lattice stabilized and such atoms undergo oxidation at unusually low potentials within the double layer region. Dramatic examples of such behaviour are shown in Figures 3 and 4: as pointed out earlier (25) there is independent evidence for such behaviour in the case of cathodically pretreated gold (27) and gold single crystal surfaces.…”

Section: The Anomalous Electrochemical Behaviour Of Goldmentioning

confidence: 99%

High energy states of goldand their importance in electrocatalytic processes at surfaces and interfaces

2002

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The ability of metals to store or trap considerable amounts of energy, and thus exist in a non-equilibrium or metastable state, is very well known in metallurgy; however, such behaviour, which is intimately connected with the defect character of metals, has been largely ignored in noble metal surface electrochemistry. Techniques for generating unusually high energy surface states for gold, and the unusual voltammetric responses of such states, are outlined. The surprisingly high (and complex) electrocatalytic activity of gold in aqueous media is attributed to the presence of a range of such non-equilibrium states as the vital entities at active sites on conventional gold surfaces. The possible relevance of these ideas to account for the remarkable catalytic activity of oxidesupported gold microparticles is briefly outlined.From a technological viewpoint heterogeneous catalysis is one of the most important areas of chemistry; in new technology such processes are responsible for over 90% of chemical and petroleum products by value (1). It is widely accepted (1) that a vital objective in this area is to identify the nature and mode of operation of surface active sites; this task was designated recently by Roberts (2) as "the ultimate in catalytic research". The problems involved appear quite daunting as, despite extensive investigation involving a vast array of sophisticated techniques, the general impression (for the vast majority of catalytic processes) is that "catalytic sites remain unidentified" (3).The active site theory of heterogeneous catalysis was proposed by Taylor (4) in 1925. Along with the suggestion that only a small percentage of surface atoms participate in such reactions, he pointed out that the sites in question "manifest an extraordinary sensitivity to heat treatment". He attributed the latter to the incomplete crystallization of the active site material, ie the latter (as discussed here later) usually exists in a metastable, non-equilibrium state. By inducing crystallization, the heat treatment eliminates the active sites and the resulting more stable material produced at the surface is relatively inactive. Taylor's suggestions are in agreement with current ideas in the surface science approach to surface catalysis, eg Somorjai (5) pointed out recently that, for the same surface, catalytic processes occur much more rapidly at defects (the metal atoms (Med) associated with defects are intrinsically active, ie μ(Med) > μ°(Me)), such as kinks and ledges, than on terraces; he also stressed that "rough [disordered or non-equilibrated] surfaces do chemistry", ie they are the most active from a catalytic viewpoint.In the present article the main emphasis is on electrocatalysis, ie the catalysis of faradaic reactions, and in particular on the behaviour of gold in aqueous media. This work may be regarded as an extension of an earlier 2-part review (6, 7) of the electrocatalytic properties of the same metal. Attention is focused on such topics as metastable, non-equilibrium or defect states of metals, me...

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“…For electrodeposition of Cu/M (M = Ag, Au, Pd), an inert graphite rod (3 mm diameter, Johnson Matthey Ultra "F" purity grade) was used as the counter electrode to avoid any possible contaminants from electrodissolution. [24] All electrochemical measurements commenced after degassing the electrolyte solutions with nitrogen for 10 min prior to any measurement. Current density was reported by taking the geometric area of the sample into account.…”

Section: Discussionmentioning

confidence: 99%

Cathodic Corrosion of Cu Substrates as a Route to Nanostructured Cu/M (M=Ag, Au, Pd) Surfaces

2014

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The electrochemical formation of nanostructured materials is generally achieved by reduction of a metal salt onto a substrate that does not influence the composition of the deposit. In this work, we report that Ag, Au and Pd electrodeposited onto Cu under conditions where galvanic replacement is not viable and hydrogen gas is evolved results in the formation of nanostructured surfaces that unexpectedly incorporate a high concentration of Cu in the final material. Under cathodic polarisation conditions, the electrodissolution/corrosion of Cu occurs, which provides a source of ionic copper that is reduced at the surface–electrolyte interface. The nanostructured Cu/M (M=Ag, Au and Pd) surfaces are investigated for their catalytic activity for the reduction of 4‐nitrophenol by NaBH4, where Cu/Ag was found to be extremely active. This work indicates that a substrate electrode can be utilised in an interesting manner to make bimetallic nanostructures with enhanced catalytic activity.

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Auto-inhibition of hydrogen gas evolution on gold in aqueous acid solution

Cited by 34 publications

References 0 publications

Scope for new applications for gold arising from the electrocatalytic behaviour of its metastable surface states

Scope for new applications for gold arising from the electrocatalytic behaviour of its metastable surface states

High energy states of goldand their importance in electrocatalytic processes at surfaces and interfaces

Cathodic Corrosion of Cu Substrates as a Route to Nanostructured Cu/M (M=Ag, Au, Pd) Surfaces

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