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Enhanced hydrogen formation during the catalytic decomposition of H2O2 on metal oxide surfaces in the presence of HO radical scavengers
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0002-0086-5536
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0003-0663-0751
2013 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 30, 12674-12679 p.Article in journal (Refereed) Published
Abstract [en]

Presently and for the foreseeable future, hydrogen peroxide and transition metal oxides are important constituents of energy production processes. In this work, the effect of the presence of HO radical scavengers on the product yield from the decomposition of H2O2 on metal oxide surfaces in aqueous solution was examined experimentally. Scavenging the intermediate product HO center dot by means of Tris or TAPS buffer leads to enhanced formation of H-2. In parallel, a decrease in the production of the main gaseous product O-2 is observed. Under these conditions, H-2 formation is a spontaneous process even at room temperature. The yields of both the H-2 and O-2 depend on the concentration of Tris or TAPS in the reaction media. We observed that TAPS has a higher affinity for the surface of ZrO2 than does Tris. The difference in adsorption of both scavengers is reflected by the difference in their influence on the product yields. The observed sensitivity of the system H2O2-ZrO2 towards the two different scavengers indicates that O-2 and H-2 are formed at different types of surface sites.

Place, publisher, year, edition, pages
2013. Vol. 15, no 30, 12674-12679 p.
Keyword [en]
Hydroxyl Radicals, Mgo(100) Surfaces, Methylene-Blue, Peroxide, Water, Reactivity, Tio2(110), Mechanism, Energy, DFT
National Category
Physical Chemistry
URN: urn:nbn:se:kth:diva-119807DOI: 10.1039/c3cp51616dISI: 000321622500034ScopusID: 2-s2.0-84881139845OAI: diva2:612592

QC 20130814

Available from: 2013-03-22 Created: 2013-03-22 Last updated: 2013-08-14Bibliographically approved
In thesis
1. Reactions of aqueous radiolysis products with oxide surfaces: An experimental and DFT study
Open this publication in new window or tab >>Reactions of aqueous radiolysis products with oxide surfaces: An experimental and DFT study
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The reactions between aqueous radiolysis products and oxide surfaces are important in nuclear technology in many ways. In solid-liquid systems, they affect (and at the same time are dependent on) both the solution chemistry and the stability of materials under the influence of ionizing radiation. The stability of surface oxides is a factor that determines the longevity of the materials where such oxides are formed. Additionally, the aqueous radiolysis products are responsible for corrosion and erosion of the materials.

  In this study, the reactions between radiolysis products of water – mainly H2O2 and HO radicals – with metal, lanthanide and actinide oxides are investigated. For this, experimental and computational chemistry methods are employed. For the experimental study of these systems it was necessary to implement new methodologies especially for the study of the reactive species – the HO radicals. Similarly, the computational study also required the development of models and benchmarking of methods. The experiments combined with the computational chemistry studies produced valuable kinetic, energetic and mechanistic data.

  It is demonstrated here that the HO radicals are a primary product of the decomposition of H2O2. For all the materials, the catalytic decomposition of H2O2 consists first of molecular adsorption onto the surfaces of the oxides. This step is followed by the cleavage of the O-O bond in H2O2 to form HO radicals. The HO radicals are able to react further with the hydroxylated surfaces of the oxides to form water and a surface bound HO center. The dynamics of formation of HO vary widely for the different materials studied. These differences are also observed in the activation energies and kinetics for decomposition of H2O2. It is found further that the removal of HO from the system where H2O2 undergoes decomposition, by means of a scavenger, leads to the spontaneous formation of H2.

  The combined theoretical-experimental methodology led to mechanistic understanding of the reactivity of the oxide materials towards H2O2 and HO radicals. This reactivity can be expressed in terms of fundamental properties of the cations present in the oxides. Correlations were found between several properties of the metal cations present in the oxides and adsorption energies of H2O, adsorption energies of HO radicals and energy barriers for H2O2 decomposition. This knowledge can aid in improving materials and processes important for nuclear technological systems, catalysis, and energy storage, and also help to better understand geochemical processes.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 121 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2013:12
hydrogen peroxide, hydrogen production, metal, oxides, lanthanide, catalysis, density functional theory, surface, reactions, chemistry
National Category
Physical Chemistry Materials Chemistry Theoretical Chemistry
Research subject
SRA - Energy; SRA - Production
urn:nbn:se:kth:diva-119780 (URN)978-91-7501-683-2 (ISBN)
Public defence
2013-04-12, K2, Teknikringen 28, KTH, Stockholm, 10:00 (English)
StandUpXPRES - Initiative for excellence in production research

QC 20130322

Available from: 2013-03-22 Created: 2013-03-21 Last updated: 2013-03-22Bibliographically approved

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