Tuning the properties of visible-light-responsive tantalum (oxy)nitride photocatalysts by non-stoichiometric compositions: A first-principles viewpoint

Handle URI:
http://hdl.handle.net/10754/563240
Title:
Tuning the properties of visible-light-responsive tantalum (oxy)nitride photocatalysts by non-stoichiometric compositions: A first-principles viewpoint
Authors:
Harb, Moussab ( 0000-0001-5540-9792 ) ; Sautet, Philippe; Nurlaela, Ela; Raybaud, Pascal; Cavallo, Luigi ( 0000-0002-1398-338X ) ; Domen, Kazunari; Basset, Jean-Marie ( 0000-0003-3166-8882 ) ; Takanabe, Kazuhiro ( 0000-0001-5374-9451 )
Abstract:
Finding an ideal photocatalyst for achieving efficient overall water splitting still remains a great challenge. By applying accurate first-principles quantum calculations based on DFT with the screened non-local hybrid HSE06 functional, we bring rational insights at the atomic level into the influence of non-stoichiometric compositions on essential properties of tantalum (oxy)nitride compounds as visible-light-responsive photocatalysts for water splitting. Indeed, recent experiments show that such non-stoichiometry is inherent to the nitridation methods of tantalum oxide with unavoidable oxygen impurities. We considered here O-enriched Ta3N5 and N-enriched TaON materials. Although their structural parameters are found to be very similar to those of pure compounds and in good agreement with available experimental studies, their photocatalytic features for visible-light-driven overall water splitting reactions show different behaviors. Further partial nitration of TaON leads to a narrowed band gap, but partially oxidizing Ta3N5 causes only subtle changes in the gap. The main influence, however, is on the band edge positions relative to water redox potentials. The pure Ta3N5 is predicted to be a good candidate only for H+ reduction and H2 evolution, while the pure TaON is predicted to be a good candidate for water oxidation and O2 evolution. Non-stoichiometry has here a positive influence, since partially oxidized tantalum nitride, Ta(3-x)N(5-5x)O5x (for x ≥ 0.16) i.e. with a composition in between TaON and Ta3N5, reveals suitable band edge positions that correctly bracket the water redox potentials for visible-light-driven overall water splitting reactions. Among the various explored Ta(3-x)N(5-5x)O5x structures, a strong stabilization is obtained for the configuration displaying a strong interaction between the O-impurities and the created Ta-vacancies. In the lowest-energy structure, each created Ta-vacancy is surrounded by five O-impurity species substituting the five N sites characterizing one octahedral environment. This journal is
KAUST Department:
KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division; Chemical Science Program; Catalysis for Energy Conversion (CatEC)
Publisher:
Royal Society of Chemistry (RSC)
Journal:
Phys. Chem. Chem. Phys.
Issue Date:
2014
DOI:
10.1039/c4cp03594a
Type:
Article
ISSN:
14639076
Sponsors:
This work was supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors gratefully thank the High Performance Computing department (HPC) at KAUST for the computational time granted to this work.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorHarb, Moussaben
dc.contributor.authorSautet, Philippeen
dc.contributor.authorNurlaela, Elaen
dc.contributor.authorRaybaud, Pascalen
dc.contributor.authorCavallo, Luigien
dc.contributor.authorDomen, Kazunarien
dc.contributor.authorBasset, Jean-Marieen
dc.contributor.authorTakanabe, Kazuhiroen
dc.date.accessioned2015-08-03T11:43:53Zen
dc.date.available2015-08-03T11:43:53Zen
dc.date.issued2014en
dc.identifier.issn14639076en
dc.identifier.doi10.1039/c4cp03594aen
dc.identifier.urihttp://hdl.handle.net/10754/563240en
dc.description.abstractFinding an ideal photocatalyst for achieving efficient overall water splitting still remains a great challenge. By applying accurate first-principles quantum calculations based on DFT with the screened non-local hybrid HSE06 functional, we bring rational insights at the atomic level into the influence of non-stoichiometric compositions on essential properties of tantalum (oxy)nitride compounds as visible-light-responsive photocatalysts for water splitting. Indeed, recent experiments show that such non-stoichiometry is inherent to the nitridation methods of tantalum oxide with unavoidable oxygen impurities. We considered here O-enriched Ta3N5 and N-enriched TaON materials. Although their structural parameters are found to be very similar to those of pure compounds and in good agreement with available experimental studies, their photocatalytic features for visible-light-driven overall water splitting reactions show different behaviors. Further partial nitration of TaON leads to a narrowed band gap, but partially oxidizing Ta3N5 causes only subtle changes in the gap. The main influence, however, is on the band edge positions relative to water redox potentials. The pure Ta3N5 is predicted to be a good candidate only for H+ reduction and H2 evolution, while the pure TaON is predicted to be a good candidate for water oxidation and O2 evolution. Non-stoichiometry has here a positive influence, since partially oxidized tantalum nitride, Ta(3-x)N(5-5x)O5x (for x ≥ 0.16) i.e. with a composition in between TaON and Ta3N5, reveals suitable band edge positions that correctly bracket the water redox potentials for visible-light-driven overall water splitting reactions. Among the various explored Ta(3-x)N(5-5x)O5x structures, a strong stabilization is obtained for the configuration displaying a strong interaction between the O-impurities and the created Ta-vacancies. In the lowest-energy structure, each created Ta-vacancy is surrounded by five O-impurity species substituting the five N sites characterizing one octahedral environment. This journal isen
dc.description.sponsorshipThis work was supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors gratefully thank the High Performance Computing department (HPC) at KAUST for the computational time granted to this work.en
dc.publisherRoyal Society of Chemistry (RSC)en
dc.titleTuning the properties of visible-light-responsive tantalum (oxy)nitride photocatalysts by non-stoichiometric compositions: A first-principles viewpointen
dc.typeArticleen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.contributor.departmentCatalysis for Energy Conversion (CatEC)en
dc.identifier.journalPhys. Chem. Chem. Phys.en
dc.contributor.institutionUniv Lyon, CNRS, Ecole Normale Super Lyon, Lab Chim, F-69364 Lyon 07, Franceen
dc.contributor.institutionIFP Energies Nouvelles, Rond Point Echangeur Solaize, F-69360 Solaize, Franceen
dc.contributor.institutionUniv Tokyo, Dept Chem Syst Engn, Bunkyo Ku, Tokyo 1138656, Japanen
kaust.authorHarb, Moussaben
kaust.authorCavallo, Luigien
kaust.authorBasset, Jean-Marieen
kaust.authorTakanabe, Kazuhiroen
kaust.authorNurlaela, Elaen
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