Establishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst

Handle URI:
http://hdl.handle.net/10754/565796
Title:
Establishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst
Authors:
Nurlaela, Ela; Ould-Chikh, Samy ( 0000-0002-3486-0944 ) ; Llorens, Isabelle; Hazemann, Jean-louis; Takanabe, Kazuhiro ( 0000-0001-5374-9451 )
Abstract:
In a photocatalytic suspension system with a powder semiconductor, the interface between the photocatalyst semiconductor and catalyst should be constructed to minimize resistance for charge transfer of excited carriers. This study demonstrates an in-depth understanding of pretreatment effects on the photocatalytic O2 evolution reaction (OER) activity of visible-light-responsive Ta3N5 decorated with CoOx nanoparticles. The CoOx/Ta3N5 sample was synthesized by impregnation followed by sequential heat treat-ments under NH3 flow and air flow at various temperatures. Various characterization techniques, including X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spec-troscopy (XPS), were used to clarify the state and role of cobalt. No improvement in photocatalytic activity for OER over the bare Ta3N5 was observed for the as-impregnated CoOx/Ta3N5, likely because of insufficient contact between CoOx and Ta3N5. When the sample was treated in NH3 at high temperature, a substantial improvement in the photocatalytic activity was observed. After NH3 treatment at 700 °C, the Co0-CoOx core-shell agglomerated cobalt structure was identified by XAS and STEM. No metallic cobalt species was evident after the photocatalytic OER, indicating that the metallic cobalt itself is not essential for the reaction. Accordingly, mild oxidation (200 °C) of the NH3-treated CoOx/Ta3N5 sample enhanced photocatalytic OER activity. Oxidation at higher temperatures drastically eliminated the photocatalytic activity, most likely because of unfavorable Ta3N5 oxidation. These results suggest that the intimate contact between cobalt species and Ta3N5 facilitated at high temperature is beneficial to enhancing hole transport and that the cobalt oxide provides electrocatalytic sites for OER.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
Establishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst 2015:150805135245001 Chemistry of Materials
Publisher:
American Chemical Society (ACS)
Journal:
Chemistry of Materials
Issue Date:
5-Aug-2015
DOI:
10.1021/acs.chemmater.5b02139
Type:
Article
ISSN:
0897-4756; 1520-5002
Additional Links:
http://pubs.acs.org/doi/abs/10.1021/acs.chemmater.5b02139
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorNurlaela, Elaen
dc.contributor.authorOuld-Chikh, Samyen
dc.contributor.authorLlorens, Isabelleen
dc.contributor.authorHazemann, Jean-louisen
dc.contributor.authorTakanabe, Kazuhiroen
dc.date.accessioned2015-08-10T12:16:07Zen
dc.date.available2015-08-10T12:16:07Zen
dc.date.issued2015-08-05en
dc.identifier.citationEstablishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst 2015:150805135245001 Chemistry of Materialsen
dc.identifier.issn0897-4756en
dc.identifier.issn1520-5002en
dc.identifier.doi10.1021/acs.chemmater.5b02139en
dc.identifier.urihttp://hdl.handle.net/10754/565796en
dc.description.abstractIn a photocatalytic suspension system with a powder semiconductor, the interface between the photocatalyst semiconductor and catalyst should be constructed to minimize resistance for charge transfer of excited carriers. This study demonstrates an in-depth understanding of pretreatment effects on the photocatalytic O2 evolution reaction (OER) activity of visible-light-responsive Ta3N5 decorated with CoOx nanoparticles. The CoOx/Ta3N5 sample was synthesized by impregnation followed by sequential heat treat-ments under NH3 flow and air flow at various temperatures. Various characterization techniques, including X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spec-troscopy (XPS), were used to clarify the state and role of cobalt. No improvement in photocatalytic activity for OER over the bare Ta3N5 was observed for the as-impregnated CoOx/Ta3N5, likely because of insufficient contact between CoOx and Ta3N5. When the sample was treated in NH3 at high temperature, a substantial improvement in the photocatalytic activity was observed. After NH3 treatment at 700 °C, the Co0-CoOx core-shell agglomerated cobalt structure was identified by XAS and STEM. No metallic cobalt species was evident after the photocatalytic OER, indicating that the metallic cobalt itself is not essential for the reaction. Accordingly, mild oxidation (200 °C) of the NH3-treated CoOx/Ta3N5 sample enhanced photocatalytic OER activity. Oxidation at higher temperatures drastically eliminated the photocatalytic activity, most likely because of unfavorable Ta3N5 oxidation. These results suggest that the intimate contact between cobalt species and Ta3N5 facilitated at high temperature is beneficial to enhancing hole transport and that the cobalt oxide provides electrocatalytic sites for OER.en
dc.language.isoenen
dc.publisherAmerican Chemical Society (ACS)en
dc.relation.urlhttp://pubs.acs.org/doi/abs/10.1021/acs.chemmater.5b02139en
dc.rightsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemistry of Materials, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.chemmater.5b02139.en
dc.titleEstablishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalysten
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalChemistry of Materialsen
dc.eprint.versionPost-printen
dc.contributor.institutionInstitut de Recherches sur la Catalyse et l’Enviro nnement de Lyon IRCELYON, UMR 5256, CNRS – Universi té Lyon 1, 2 av A. Einstein, 69626 Villeurbanne Cedex, Franceen
dc.contributor.institutionInstitut Néel, CNRS, 25 avenue des Martyrs, 38042 Grenoble Cedex 9, Franceen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorOuld-Chikh, Samyen
kaust.authorTakanabe, Kazuhiroen
kaust.authorNurlaela, Elaen
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