Catalytic and photocatalytic reactions of H2+CO2 on supported Au catalysts

Halasi, Gyula; Gazsi, A.; Bánsági, Tamás; Solymosi, F.

doi:10.1016/j.apcata.2015.08.035

Cited by 17 publications

(13 citation statements)

References 30 publications

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“…importance of the activation of CO 2 appeared in our recent study dealing with the catalytic and photocatalytic reaction of H 2 þ CO 2 on Au deposited on various n-type oxides [52,53].…”

Section: Catalytic Studymentioning

confidence: 99%

Production of H 2 in the photocatalytic reactions of ethane on TiO 2 -supported noble metals

Halasi¹,

Tóth²,

Bánsági³

et al. 2016

International Journal of Hydrogen Energy

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“…importance of the activation of CO 2 appeared in our recent study dealing with the catalytic and photocatalytic reaction of H 2 þ CO 2 on Au deposited on various n-type oxides [52,53].…”

Section: Catalytic Studymentioning

confidence: 99%

Production of H 2 in the photocatalytic reactions of ethane on TiO 2 -supported noble metals

Halasi¹,

Tóth²,

Bánsági³

et al. 2016

International Journal of Hydrogen Energy

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“…It involves the activation and cleavage of the strong carbon-oxygen bonds and a subsequent establishment of new chemistry with higher enthalpy [57][58][59]. Once the surprisingly high catalytic activity of nanosized Au has been discovered in many reactions, its influence on the catalytic chemistry of CO 2 has also been tested [8,48,60,61]. Here we focus on comparing the thermal and the photo-induced CO 2 + H 2 reactions on titanate-supported Au catalysts.…”

Section: Photocatalytic Reaction Of Co 2 + H 2 On Au/tntmentioning

confidence: 99%

“…We hypothesize that the photocatalytic reduction of CO 2 takes place through surface formates. The first step is the activation of CO 2 , in which a radical anion (CO 2 *− ) is formed [57,58,61] On the other hand, UV irradiation can also generate e − (Ti 4+ ) electrons, which results in the formation of carboxylates in the presence of CO 2 [48,68].…”

Section: Photocatalytic Reaction Of Co 2 + H 2 On Au/tntmentioning

confidence: 99%

Beyond Nanoparticles: The Role of Sub-nanosized Metal Species in Heterogeneous Catalysis

Kiss

Kukovecz

2019

Catal Lett

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Titanate nanostructures are of great interest for catalytic applications because their high surface area and cation exchange capacity create the possibility to achieve high metal dispersion. Ion exchange allows titanate nanostructures to incorporate metal adatoms in their framework. Consequently, the curved layers contain a large amount of defect sites, typically oxygen vacancies and Ti 3+ centers, which can make them promising photocatalysts, because the defect sites can trap photoelectrons or holes extending the lifetime of the excited state. Due to the large amount of defects, titanate nanotubes (TNT) can stabilize sub-nanosized gold clusters, presumably in Au 25 form. This perspective summarizes the previous results obtained in the photocatalytic transformation of methane in which the size of gold nanoclusters plays an important role. Photocatalytic measurements revealed that methane is active towards photo-oxidation. Methane transforms mainly into hydrogen and, to a lesser extent, to ethane and ethanol. Based on recent additional results, we stress here that gold clusters (Au 25) may be directly involved in the photo-induced reactions, namely in the direct activation of the methane/Au 25 δ+ complex during irradiation. Another new finding is that gold nanoparticles supported on TNT exhibit high catalytic activity in CO 2 hydrogenation. Our results revealed fundamental differences in the reaction schemes as the products of the two routes are CO (thermal process) and CH 4 (photocatalytic route), indicating the importance of photogenerated electron-hole pairs in the reaction. The presence of gold nanoparticles on the surface has been found to have multiple roles. On the one hand, gold in nano and sub-nano sizes promotes the adsorption and scission of reactants, important for both types of reactions. On the other hand, the gold-support interface forms a rectifying Schottky contact that helps in the separation of photogenerated carriers, thus improving the utilization of electrons and holes in the reduction and oxidation steps, respectively. Furthermore, gold ions (Au +), in the cationic sites of the titanate lattice promote the photocatalytic transformation of formate (which is one of the intermediates), thus advancing the reaction further towards the fully reduced product. The explored reaction schemes may pave the road towards novel catalytic materials that can solve challenges associated with the activation of CH 4 and CO 2 and thus contribute to green chemistry.

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“…Samples were taken from the gas stream at the inlet and the outlet of the reactor during the experiments and the signal differences (signal at inlet subtracted from the signal at outlet) were used further in the evaluations. The signal intensity y i (t) at the 2, 15, 16,18,26,27,28,29,30,31,43,44 and 45 m/z values ( y i (t) refers to the differential signal) were followed. The spectrometer was previously calibrated for all expected products.…”

Section: Photocatalytic Testsmentioning

confidence: 99%

“…It is chemically and biologically stable and possesses high oxidative potential. UV-irradiation generates electron-hole pairs in TiO 2 like in other semiconductors, which ends in powerful redox centers on the surface [23][24][25][26][27][28][29]. TiO 2 and its derivatives were reported in many papers as photocatalysts in the carbon-dioxide reduction [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen evolution in the photocatalytic reaction between methane and water in the presence of CO2 on titanate and titania supported Rh and Au catalysts

et al. 2018

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The photocatalytic transformation of methane-water mixture over Rh and Au catalysts supported on protonated (H-form) titanate nanotube (TNT) was investigated. The role of the catalyst structure was analyzed using titania reference support. Furthermore the effect of carbon-dioxide addition was also investigated. The catalysts were characterized by high resolution transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). Photocatalytic tests were performed with a mercury-arc UV source illuminating a continuous flow quartz reactor which was attached to a mass spectrometer. The surface of the catalysts was analyzed by diffuse reflectance infrared spectroscopy during the photoreactions. The changes of the catalysts due to photocatalytic usage were investigated by XPS and temperature programmed reduction methods as well. Most of the methane was generally transformed to hydrogen and ethane, and a small amount of methanol was also formed. The carbon dioxide addition enhanced the rate of the photocatalytic transformation of methane on Rh/TNT with increasing the lifetime of the electron-hole pairs. Bigger gold particles with mainly plasmonic character were more active in the reactions due to the photo induced activation of the adsorbed water. Surface carbon deposits were identified on the catalysts after the photoreactions. More oxidized carbon formed on the Au-containing catalysts than on the ones with Rh. Graphical AbstractKeywords Heterogeneous photocatalysis · Titanate nanotube · Gold nanoparticle · Molecular-like cluster · Surface plasmon resonance

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Catalytic and photocatalytic reactions of H2+CO2 on supported Au catalysts

Cited by 17 publications

References 30 publications

Production of H 2 in the photocatalytic reactions of ethane on TiO 2 -supported noble metals

Production of H 2 in the photocatalytic reactions of ethane on TiO 2 -supported noble metals

Beyond Nanoparticles: The Role of Sub-nanosized Metal Species in Heterogeneous Catalysis

Hydrogen evolution in the photocatalytic reaction between methane and water in the presence of CO2 on titanate and titania supported Rh and Au catalysts

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