A DFT+U study of the Mars Van Krevelen mechanism of CO oxidation on Au/TiO2 catalysts

Saqlain, Muhammad Adnan; Hussain, Akhtar; Siddiq, Muhammad; Leitão, Alexandre A.

doi:10.1016/j.apcata.2016.03.021

Cited by 42 publications

(31 citation statements)

References 61 publications

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“…12 However, for the most active Au catalysts, the oxidation of CO is thought to involve the activation of oxygen at the interface of the nanoparticles and reducible supports 13 (TiO2, 14 FeOx, 15,16 CeO2 17 ) with models showing that oxygen can be delivered in a Mars-van Krevelen (MvK) process. 18,19 There is a barrier to removal of lattice oxygen in this MvK pathway, so that at very low temperatures (around 130 K) CO oxidation using Au/TiO2 will revert to the Au only mechanism seen on non-reducible supports. 20 The important influence of supports on the reactivity of Au nanoparticles has recently been reviewed.…”

Section: Introductionmentioning

confidence: 99%

The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study

et al. 2021

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Catalysts consisting of Au, Pd and their alloys have been shown to be active oxidation catalysts. These materials can use dioxygen or hydrogen peroxide as the oxidant with CO and activated organic molecules using O2(g) while more challenging cases, such as methane to partial oxygenates, relying on H2O2. Although H2O2 is a green oxidant, the incorporation of dioxygen greatly reduces overall cost and so there is an incentive to find new ways to reduce the reliance on H2O2. In this study we use DFT calculations to discuss the direct synthesis of H2O2 from H2(g) and O2(g) and use this understanding to identify the important surface species derived from dioxygen. We cover the adsorption of oxygen, hydrogen and water to model Au and Pd nanoclusters and the oxidation of the metals, since reduction of any oxides formed will consume H2. We then turn to the production of a surface hydroperoxy species; the first step in the synthesis of H2O2. This can occur via hydrogenation of O2(ads) with H2(ads) or via protonation of O2(ads) by solvent water. Both routes are found to be energetically reasonable, but the latter is likely to be favoured under experimental conditions.

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Section: Introductionmentioning

confidence: 99%

The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study

et al. 2021

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“…In redox reactions, the crucial steps are the transfer of the substrate oxygen atoms into the adsorbed reactants and the filling of the vacancies by dissociating O 2 originated from the reaction media. This mechanism is known as the Mars–van Krevelen phenomena and it is known for several compounds such as for CeO 2 , V 2 O 3 , BiOCl and TiO 2 [ 28 , 29 , 30 , 31 ].…”

Section: Resultsmentioning

confidence: 99%

Hydrothermal Crystallization of Bismuth Oxychlorides (BiOCl) Using Different Shape Control Reagents

et al. 2021

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Bismuth oxychloride photocatalysts were obtained using solvothermal synthesis and different additives (CTAB—cetyltrimethylammonium bromide, CTAC—cetyltrimethylammonium chloride, PVP–polyvinylpyrrolidone, SDS–sodium dodecylsulphate, U—urea and TU—thiourea). The effect of the previously mentioned compounds was analyzed applying structural (primary crystallite size, crystal phase composition, etc.), morphological (particle geometry), optical (band gap energy) parameters, surface related properties (surface atoms’ oxidation states), and the resulted photocatalytic activity. A strong dependency was found between the surface tension of the synthesis solutions and the overall morpho-structural parameters. The main finding was that the characteristics of the semiconductors can be tuned by modifying the surface tension of the synthesis mixture. It was observed after the photocatalytic degradation, that the white semiconductor turned to grey. Furthermore, we attempted to explain the gray color of BiOCl catalysts after the photocatalytic decompositions by Raman and XPS studies.

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“…Saqlain et al. investigated by means of DFT+U calculations the role of Au clusters in facilitating the formation of surface oxygen vacancies on anatase (001) ,. In presence of Au clusters, a clear decrease of the oxygen vacancy formation free energy, ΔG°(V O ), was reported at Au 10 /TiO 2 perimeter sites with respect to the Au‐free titania surface.…”

Section: Applications In Heterogeneous Catalysismentioning

confidence: 99%

Oxide‐Supported Gold Clusters and Nanoparticles in Catalysis: A Computational Chemistry Perspective

Tosoni

Pacchioni

2018

ChemCatChem

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This review provides an insight into the simulation of gold nanoparticles supported on oxide surfaces, with particular emphasis on the applications in heterogeneous catalysis. Some important methodological issues are firstly addressed: the polymorphism of small gold clusters, the difficulty in determining the actual charge state of adsorbed gold atoms, the relevance of long‐range dispersion and relativistic effects and the size‐effects in modelling Au nanoparticles. Then, the adsorption of Au species on oxides is addressed by comparing bulk oxides to ultrathin oxide films supported on metals. The role of defects as nucleation centres is also discussed. Finally, this review addresses the contribution from computational studies on the mechanisms involving Au‐based heterogeneous catalysts in important reactions such as the CO oxidation, the water‐gas shift reaction and the CO2 hydrogenation to methanol.

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A DFT+U study of the Mars Van Krevelen mechanism of CO oxidation on Au/TiO2 catalysts

Cited by 42 publications

References 61 publications

The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study

The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study

Hydrothermal Crystallization of Bismuth Oxychlorides (BiOCl) Using Different Shape Control Reagents

Oxide‐Supported Gold Clusters and Nanoparticles in Catalysis: A Computational Chemistry Perspective

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