A Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?

Handle URI:
http://hdl.handle.net/10754/564034
Title:
A Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?
Authors:
Sinatra, Lutfan ( 0000-0001-7034-7745 ) ; LaGrow, Alec P.; Peng, Wei ( 0000-0002-7168-9795 ) ; Kirmani, Ahmad R. ( 0000-0002-8351-3762 ) ; Amassian, Aram ( 0000-0002-5734-1194 ) ; Idriss, Hicham; Bakr, Osman M. ( 0000-0002-3428-1002 )
Abstract:
Photo-catalytic H2 production from water has been studied over Au-Cu2O nanoparticle deposited on TiO2 (anatase) in order to probe into both the plasmon resonance effect (Au nanoparticles) and the pn-junction at the Cu2O-TiO2 interface. The Au-Cu2O composite is in the form of ∼10 nm Au nanoparticles grown on ∼475 nm Cu2O octahedral nanocrystals with (111) facets by partial galvanic replacement. X-ray Photoelectron Spectroscopy (XPS) Cu2p and Auger L3M4,5M4,5 lines indicate that the surface of Cu2O is mainly composed of Cu+. The rate for H2 production (from 95 water/5 ethylene glycol; vol.%) over 2 wt.% (Au/Cu2O)-TiO2 is found to be ∼10 times faster than that on 2 wt.% Au-TiO2 alone. Raman spectroscopy before and after reaction showed the disappearance of Cu+ lines (2Eu) at 220 cm-1. These observations coupled with the induction time observed for the reaction rate suggest that in situ reduction from Cu+ to Cu0 occurs upon photo-excitation. The reduction requires the presence of TiO2 (electron transfer). The prolonged activity of the reaction (with no signs of deactivation) despite the reduction to Cu0 indicates that the latter takes part in the reaction by providing additional sites for the reaction, most likely as recombination centers for hydrogen atoms to form molecular hydrogen. This phenomenon provides an additional route for enhancing the efficiency and lifetime of Cu2O-TiO2 photocatalytic systems, beyond the usually ascribed pn-junction effect.
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Solar and Photovoltaic Engineering Research Center (SPERC); SABIC - Corporate Research and Innovation Center (CRI) at KAUST; Materials Science and Engineering Program; Organic Electronics and Photovoltaics Group; Functional Nanomaterials Lab (FuNL)
Publisher:
Elsevier BV
Journal:
Journal of Catalysis
Issue Date:
Feb-2015
DOI:
10.1016/j.jcat.2014.11.012
Type:
Article
ISSN:
00219517
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program; Solar and Photovoltaic Engineering Research Center (SPERC)

Full metadata record

DC FieldValue Language
dc.contributor.authorSinatra, Lutfanen
dc.contributor.authorLaGrow, Alec P.en
dc.contributor.authorPeng, Weien
dc.contributor.authorKirmani, Ahmad R.en
dc.contributor.authorAmassian, Aramen
dc.contributor.authorIdriss, Hichamen
dc.contributor.authorBakr, Osman M.en
dc.date.accessioned2015-08-03T12:29:15Zen
dc.date.available2015-08-03T12:29:15Zen
dc.date.issued2015-02en
dc.identifier.issn00219517en
dc.identifier.doi10.1016/j.jcat.2014.11.012en
dc.identifier.urihttp://hdl.handle.net/10754/564034en
dc.description.abstractPhoto-catalytic H2 production from water has been studied over Au-Cu2O nanoparticle deposited on TiO2 (anatase) in order to probe into both the plasmon resonance effect (Au nanoparticles) and the pn-junction at the Cu2O-TiO2 interface. The Au-Cu2O composite is in the form of ∼10 nm Au nanoparticles grown on ∼475 nm Cu2O octahedral nanocrystals with (111) facets by partial galvanic replacement. X-ray Photoelectron Spectroscopy (XPS) Cu2p and Auger L3M4,5M4,5 lines indicate that the surface of Cu2O is mainly composed of Cu+. The rate for H2 production (from 95 water/5 ethylene glycol; vol.%) over 2 wt.% (Au/Cu2O)-TiO2 is found to be ∼10 times faster than that on 2 wt.% Au-TiO2 alone. Raman spectroscopy before and after reaction showed the disappearance of Cu+ lines (2Eu) at 220 cm-1. These observations coupled with the induction time observed for the reaction rate suggest that in situ reduction from Cu+ to Cu0 occurs upon photo-excitation. The reduction requires the presence of TiO2 (electron transfer). The prolonged activity of the reaction (with no signs of deactivation) despite the reduction to Cu0 indicates that the latter takes part in the reaction by providing additional sites for the reaction, most likely as recombination centers for hydrogen atoms to form molecular hydrogen. This phenomenon provides an additional route for enhancing the efficiency and lifetime of Cu2O-TiO2 photocatalytic systems, beyond the usually ascribed pn-junction effect.en
dc.publisherElsevier BVen
dc.subjectCu2O(111) Ramanen
dc.subjectEnergy band positionen
dc.subjectHydrogen productionen
dc.subjectpn-Junctionen
dc.subjectXPS-Cu2pen
dc.titleA Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?en
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentSolar and Photovoltaic Engineering Research Center (SPERC)en
dc.contributor.departmentSABIC - Corporate Research and Innovation Center (CRI) at KAUSTen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.contributor.departmentOrganic Electronics and Photovoltaics Groupen
dc.contributor.departmentFunctional Nanomaterials Lab (FuNL)en
dc.identifier.journalJournal of Catalysisen
kaust.authorAmassian, Aramen
kaust.authorBakr, Osman M.en
kaust.authorSinatra, Lutfanen
kaust.authorLaGrow, Alec P.en
kaust.authorPeng, Weien
kaust.authorKirmani, Ahmad R.en
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