Selective Knockout of Gold Active Sites

Nowicka, Anna M.; Hasse, Ulrich; Sievers, Gustav; Donten, Mikołaj; Stojek, Zbigniew; Fletcher, Stephen; Scholz, Fritz

doi:10.1002/anie.201000485

Cited by 67 publications

(38 citation statements)

References 22 publications

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“…In contrast, metastable states are often of low lattice coordination and as a result are thermodynamically active. Nowicka et al [36] have shown that these sites can be selectively 'knocked out' by treatment with hydroxyl radicals, suggesting that surface defects are the loci of partially filled d-orbitals that can stabilise free-radical intermediates. Similarly, theoretical calculations performed by Sun et al [37] on the adsorption of oxygen on Au surfaces further highlight the role of such defect sites in surface catalysis.…”

Section: Introductionmentioning

confidence: 98%

The mechanism of oxygen evolution at superactivated gold electrodes in aqueous alkaline solution

Doyle¹,

Lyons²

2014

J Solid State Electrochem

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The cathodic superactivation of gold using a repetitive potential cycling procedure is reported, and its significance for the oxygen evolution reaction is discussed. The superactivated surfaces exhibit a transient oxygen evolution response subsequent to monolayer oxidation and prior to extensive visible oxygen evolution. The kinetics of this oxygen evolution process are studied using a variety of transient and steady-state electrochemical techniques. The Tafel slope is shown to decrease with increased activation of the gold surface from ca. 120 to ca. 48 mV dec −1 , and the charge transfer kinetics are enhanced by over three orders of magnitude for the superactivated electrodes. A mechanistic scheme involving the formation of monomeric Au(III) hydroxyl complexes of the form Au(OH) 6 3− is proposed. The latter are of a transient nature and may be regarded as intermediates in the early stages of hydrous ß-oxide growth. These labile species may catalyse oxygen evolution by enhancing the formation of peroxy species that subsequently decompose with loss of oxygen gas from the surface oxide. This novel mechanistic route is in excellent agreement with recent literature studies and has the potential to unite a number of strands in the current understanding of the oxygen evolution reaction at gold surfaces.

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Section: Introductionmentioning

confidence: 98%

The mechanism of oxygen evolution at superactivated gold electrodes in aqueous alkaline solution

Doyle¹,

Lyons²

2014

J Solid State Electrochem

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“…1 shows cyclic voltammograms for p-hydroquinone, Ru(NH 3 ) 6 3+ , ferrocenemethanol, and Fe(CN) 6 4-observed in PBS buffer. As the electrochemical behavior of p-hydroquinone highly depends on the electrocatalytic activity of an electrode, 16) p-hydroquinone was selected for the evaluation of the electrocatalytic activity. In Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of Thermal Treatment on the Electrocatalytic Activities and Surface Roughness of ITO Electrodes

Choi¹,

Jo²,

Yang³

2012

Journal of Electrochemical Science and Technology

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:The electrocatalytic activities and surface roughness of indium-tin-oxide (ITO) electrodes have been investigated after thermal treatment at 100, 150, or 200 o C for 30 min, 2 h, or 8 h. To check electrocatalytic activities, the electrochemical behavior of four electroactive species ( p-hydroquinone, Ru(NH 3 ) 6 3+, ferrocenemethanol, and Fe(CN) 6 4-) has been measured. The electron transfer rate for p-hydroquinone oxidation and ferrocenemethanol oxidation increases with increasing the incubation temperature and the incubation period of time, but the rate for Ru(NH 3 ) 6 3+ is similar irrespective of the incubation temperature and period because Ru(NH 3 ) 6 3+ undergoes a fast outer-sphere reaction. Overall, the electrocatalytic activities of ITO electrodes increase with increasing the incubation temperature and period. The surface roughness of ITO electrodes increases with increasing the incubation temperature, and the thermal treatment generates many towering pillars as high as several tens of nanometer.

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“…1A), with eight cantilevers (500 m by 100 m by 1 m) per array, were purchased from Concentris GmbH, Switzerland. They were cleaned under UV light for 1.5 h in order to remove possible impurities and smooth the gold surface (26). This step is crucial for the following functionalization step as an irregular gold surface can lead to a decrease in cantilever sensitivity (27).…”

Section: Methodsmentioning

confidence: 99%

Carbohydrate Coating Reduces Adhesion of Biofilm-Forming Bacillus subtilis to Gold Surfaces

Kesel

Mäder

Seeberger

et al. 2014

Appl Environ Microbiol

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The growth of bacterial biofilms in pipes and food tanks causes severe problems in industry. Biofilms growing on medical implants or catheters are of great concern, as they can cause serious infections and decrease the functionality of the medical device. The prevention of bacterial adhesion-the first step in colonization and biofilm formation-is therefore very important. Current research comprises alterations in surface properties, the prevention of adhesin biosynthesis, inhibition with receptor analogs, or the development of anti-adhesive vaccines. We present a new approach that allows us to study bacterial adhesion with high sensitivity in real-time while testing several different surfaces in parallel. Using the cantilever-array technique we demonstrate that coating of gold surfaces with mono-or disaccharides results in a reduction of the bacterial adhesion of the biofilmforming bacterium Bacillus subtilis NCIB 3610 to these gold surfaces. This reduction in bacterial adhesion is independent of the studied carbohydrate. Using several mutant strains, we investigate the underlying molecular interactions, and our results suggest that adhesion to gold surfaces is mediated by thiol groups present in proteins of the bacterial cell membrane or biofilm matrix proteins expressed at low levels by the wild-type strain. Furthermore, our data indicate that the adhesion of B. subtilis NCIB 3610 to carbohydrate-coated gold surfaces is facilitated by interactions between carbohydrates installed on the cantilever gold surface and an exopolysaccharide expressed by this strain. Understanding general and specific contributions of molecular interactions mediating bacterial adhesion will enable its prevention in the future.

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Selective Knockout of Gold Active Sites

Cited by 67 publications

References 22 publications

The mechanism of oxygen evolution at superactivated gold electrodes in aqueous alkaline solution

The mechanism of oxygen evolution at superactivated gold electrodes in aqueous alkaline solution

Effect of Thermal Treatment on the Electrocatalytic Activities and Surface Roughness of ITO Electrodes

Carbohydrate Coating Reduces Adhesion of Biofilm-Forming Bacillus subtilis to Gold Surfaces

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