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Bamwenda, Gratian R.; Tsubota, Susumu; Nakamura, T.; Haruta, Masatake

doi:10.1023/a:1018925008633

Cited by 675 publications

(499 citation statements)

References 15 publications

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“…Preparation techniques seem to be very important for determining the parameters and thus catalytic efficiency. However, Au has only rarely been used previously for photocatalysis, though Bamwenda et al reported that Au/TiO2 can photocatalyse the decomposition of ethanol [14] and ethylene glycol [15]; we are not aware of any reports for the photocatalytic reforming of methanol. It must be noted that Au/TiO2 is also active in the photoxidative degradation of VOCs [16], although TiO2 alone is also effective for such reactions.…”

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confidence: 94%

Photocatalysis by au nanoparticles: Reforming of methanol

et al. 2004

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Au/TiO2 catalysts were prepared by incipient wetness impregnation and tested for the room temperature photocatalytic reforming of methanol in aqueous solution to produce hydrogen. These catalysts proved to be active for this reaction, with the dependence on loading of gold showing a double maximum in yield at 0.2 and 2 weight % with a low rate below 0.01% and above 10%. A model is proposed for the reaction, involving band gap excitation of titania electrons to produce O -species which are then used to oxidise the methanol via adsorbed methoxy, which is formed by dehydrogenation on the metal component. The reaction is truly bi-functional and only takes place at the interface between the metal and the support.An ideal for the future well-being of the human population of the world (and for the biota as a whole) is to find an energy source which has the following properties: 1 It must be environmentally benign, producing minimal pollution of any kind, and taking up as little useful space as possible; 2 It must have usable energy density; 3 It should be usable on a local basis -strategically eliminating dependence upon external influences; 4 It should be economically viable, which is not as simple a point as might at first be imagined, since it involves future costs of materials and government subsidies which are currently in place for various energy sources (nuclear, for instance) and which will, in turn, relate closely to item 3;5 It needs to be technologically feasible and available. In many ways hydrogen best fits most of these points, except for 4. It fits 1, provided that it is part of a cycle, that is hydrogen is produced from water and is burned back to water to produce energy from the exothermic oxidation of hydrogen. 2 also applies, but only if the hydrogen is used at the source of production, or is transported in a densified form (for instance, as a liquid, a high pressure gas, or condensed into a microporous high surface area solid). The technology is currently available to achieve 3 and 5, though the technology certainly can be improved. 4 is the main problem, but as stated above, hydrogen may well become economically viable in the event of a big increase in the price of oil or big taxes on fossil fuels more generally, related to the pollution they cause and their strong connection to global warming. More importantly for the West, that part of the world is currently unrealistically dependent on oil supplies from unstable parts of the world. Any responsible Western state should be investing VERY heavily, right now, in alternative energy sources, one of these being renewable and minimally-polluting hydrogen production.The objective of this paper, then, is to describe one method of producing hydrogen, that is, by using photocatalysis, which has the potential to be used to split water using sunlight. However, the rates of this reaction are quite low and so the work described here focuses on the room temperature reforming of methanol, which does effectively split water. Previous work in this group [1]...

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confidence: 94%

Photocatalysis by au nanoparticles: Reforming of methanol

et al. 2004

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“…Gold nanoparticles supported on metal oxides can indeed catalyze low-temperature complete oxidation of hydrocarbons and CO, but also epoxidation reactions and hydrogenations, the NO reduction, and several other reactions as has been reviewed in the recent literature [2,3]. Perhaps the most intensively studied reaction to date is the CO oxidation on gold supported on oxides, such as iron oxide and titania [1,[4][5][6][7], and ceria [8][9][10][11], but also on non-reducible oxides, such as alumina [12][13][14][15] and silica [12]. Activity of nanoparticles of gold on non-oxide supports has also been reported [16].…”

Section: Introductionmentioning

confidence: 99%

“…There is conflicting information in the literature about the oxidation state of gold during the dry CO oxidation reaction [4,11,14,15,[25][26][27][28][29][30][31][32][33]. There is also an unresolved issue of the importance of gold particle size for this reaction [5,34,35], while a recent theoretical study finds no effect of the type of oxide support if gold clusters with a large number of cus sites are used [36].…”

Section: Introductionmentioning

confidence: 99%

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

et al. 2007

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We compare the activity and relevant gold species of nanostructured gold-cerium oxide and gold-iron oxide catalysts for the CO oxidation by dioxygen and water. Well dispersed gold nanoparticles in reduced form provide the active sites for the CO oxidation reaction on both oxide supports. On the other hand, oxidized gold species, strongly bound on the support catalyze the water-gas shift reaction. Gold species weakly bound to ceria (doped with lanthana) or iron oxide can be removed by sodium cyanide at pH ‡12. Both parent and leached catalysts were investigated. The activity of the leached gold-iron oxide catalyst in CO oxidation is approximately two orders of magnitude lower than that of the parent material. However, after exposure to H 2 up to 400°C gold diffuses out and is in reduced form on the surface, a process accompanied by a dramatic enhancement of the CO oxidation activity. Similar results were found with the gold-ceria catalysts. On the other hand, pre-reduction of the calcined leached catalyst samples did not promote their water-gas shift activity. UV-Vis, XANES and XPS were used to probe the oxidation state of the catalysts after various treatments.

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“…The influence of preparation methods on the catalytic activity for carbon monoxide oxidation was found to be very large for Au/TiOz and negligible for Pt/TiOz catalysts (21). Platinum and gold were deposited on titania by deposition precipitation, photodecomposition and impregnation.…”

Section: Preparation and Characterization Of Supported Gold Catalystsmentioning

confidence: 99%

“…Until recently much of the literature on the topic has assumed that metallic gold is the active species, but the present reviewer would like to highlight the possibility of a monolayer of gold oxide being present on the surface of the gold during oxidation reactions (22). The interface between the gold and the support and the interaction between the gold and the support also appear to be important (21). The activities are affected by the pretreatment procedures and recent work indicates that higher activities are obtained if the supported gold is not calcined (23 -25).…”

Section: Preparation and Characterization Of Supported Gold Catalystsmentioning

confidence: 99%

New Advances in Gold Catalysis Part II

Thompson¹

1999

Gold Bull

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Some of the unique features of gold catalysis were described in Part 1. Further examples of reactions catalysed by supported transition metal oxides are given in this second part. These include both selective and complete oxidation of hydrocarbons and a number of hydrogenation reactions. In fact, gold has now been demonstrated to be the element of choice for some catalytic reactions. As a result, both chemical processing and environmental applications are foreseen for supported gold catalyst systems. In this, the second of two articles, the overall current state of knowledge on gold catalysis is reviewed and some early examples of homogeneous gold catalysis, in solution, assessed.Haruta (3) has shown (Figure 1) that catalytic activity, as expressed by temperature at 50%

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Cited by 675 publications

References 15 publications

Photocatalysis by au nanoparticles: Reforming of methanol

Photocatalysis by au nanoparticles: Reforming of methanol

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

New Advances in Gold Catalysis Part II

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