Perovskite-Type LaTiO2N Oxynitrides for Solar Water Splitting: Influence of the Synthesis Conditions

Maegli, Alexandra E.; Otal, Eugenio H.; Hisatomi, Takashi; Yoon, Songhak; Leroy, Céline M.; Schäuble, Nina; Lu, Yonglai; Grätzel, Michaël; Weidenkaff, Anke

doi:10.1016/j.egypro.2012.05.218

Cited by 44 publications

(37 citation statements)

References 18 publications

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“…The estimated band-gap value of LTON is about 2.30 eV.T his value is about 0.2-0.3 eV larger than the literature values measured for LaTiO 2 Np owder samples, [9][10][11]36] which is relatedt ot he smaller nitrogen content of our films compared to the fully nitridated compound. The estimated band-gap value of LTON is about 2.30 eV.T his value is about 0.2-0.3 eV larger than the literature values measured for LaTiO 2 Np owder samples, [9][10][11]36] which is relatedt ot he smaller nitrogen content of our films compared to the fully nitridated compound.…”

Section: Resultscontrasting

confidence: 47%

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Determination of Conduction and Valence Band Electronic Structure of LaTiO_xN_y Thin Film

et al. 2017

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The nitrogen substitution into the oxygen sites of several oxide materials leads to a reduction of the band gap to the visible-light energy range, which makes these oxynitride semiconductors potential photocatalysts for efficient solar water splitting. Oxynitrides typically show a different crystal structure compared to the pristine oxide material. As the band gap is correlated to both the chemical composition and the crystal structure, it is not trivial to distinguish which modifications of the electronic structure induced by the nitrogen substitution are related to compositional and/or structural effects. Here, X-ray emission and absorption spectroscopy are used to investigate the electronic structures of orthorhombic perovskite LaTiO N thin films in comparison with films of the pristine oxide LaTiO with similar orthorhombic structure and cationic oxidation state. Experiment and theory show the expected upward shift in energy of the valence band maximum that reduces the band gap as a consequence of the nitrogen incorporation. This study also shows that the conduction band minimum, typically considered almost unaffected by nitrogen substitution, undergoes a significant downward shift in energy. For a rational design of oxynitride photocatalysts, the observed changes of both the unoccupied and occupied electronic states have to be taken into account to justify the total band-gap narrowing induced by the nitrogen incorporation.

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Section: Resultscontrasting

confidence: 47%

“…Promising oxynitride materials are TaON with ab and gap of about 2.5 eV, [5,6] GaN:ZnO solid solutions with ab and gap of about 2.7 eV, [7,8] and the perovskite-type LaTiO 2 Na nd BaTaO 2 N with band gaps of about 2.1 [9][10][11] and 1.8 eV, [12][13][14][15][16] respectively.…”

Section: Introductionmentioning

confidence: 99%

Determination of Conduction and Valence Band Electronic Structure of LaTiO_xN_y Thin Film

et al. 2017

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“…Nitrogen is less electronegative than oxygen and incorporation of N 3− into metal oxides results in a considerable reduction in the band gap since the 2p orbitals of nitrogen have a higher energy than the 2p orbitals of oxygen [2][3][4][5][6]. On nitriding La 2 Ti 2 O 7 to LaTiO 2 N, the absorption edge red shifts from 3.2 eV to 2.2 eV [2][3][4][5][6][7][8][9][10][11]. By precise control of the nitridation conditions, LaTiO 2+x N 1−x pigments with orange, yellow, green and blue colours have been synthesized [8,10].…”

Section: Introductionmentioning

confidence: 97%

“…By precise control of the nitridation conditions, LaTiO 2+x N 1−x pigments with orange, yellow, green and blue colours have been synthesized [8,10]. Further colour manipulation can be achieved through lanthanum substitution with Ca 2+ , Sr 2+ or Ba 2+ , or titanium substitution with Nb 5+ or W 6+ [8][9][10][11][12][13][14][15][16]. Recently, the introduction of tungsten has been shown to red-shift the band gap of LaTiO 2 N to 2.1 eV [16].…”

Section: Introductionmentioning

confidence: 97%

Structural and optical properties of perovskite-type LaTiO2N synthesized using urea or thiourea as co-nitriding agents

Sarda

Omune

Hayashi

et al. 2015

Journal of the European Ceramic Society

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“…Since the topmost surface layers are in direct contact with the environment, we expect their composition and structure to significantly affect photo-catalytic processes and hence the water splitting efficiency of the oxynitride. A particularly well-studied perovskite oxynitride composition is LaTiO 2 N, which was experimentally shown to successfully evolve O 2 and H 2 in the presence of sacrificial agents [12][13][14] and cocatalysts 15 . In the bulk, LaTiO 2 N was reported to be either full disordered 11,16 or to have partial ordering on the anion sub-lattice when the material is slowly cooled to room temperature, instead of being quenched 17 .…”

Section: Introductionmentioning

confidence: 99%

Surface structure and anion order of the oxynitride LaTiO₂N

Ninova

2017

J. Mater. Chem. A

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Oxynitrides are promising materials for water splitting under visible light. Members of this class of semiconductors that crystallise in the perovskite structure are often characterised by O/N disorder, while some studies observe 2D cischain ordering of the M-N-M bonds in the bulk. Despite the fact that the surface structure and composition is expected to have a significant influence on the surface chemistry and therefore the photocatalytic activity, little is known about the O/N arrangement at surfaces of these materials. In the present study, we investigate the surface structure of LaTiO 2 N, a particularly promising candidate for water splitting, using density functional theory (DFT) calculations. Based on slab calculations with different anion order we find that the N atoms prefer to form trans-chains at the (001) surface, as opposed to the bulk. This is governed by the electrostatic stability that is optimal for alternating charge-neutral (LaN)-(TiO 2 ) atomic layers. We show that polar surfaces that do not fulfil this requirement will electronically or structurally reconstruct. Our results predict that in contact with vacuum, the LaTiO 2 N (001) surface will preferentially be LaN-terminated.

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Perovskite-Type LaTiO2N Oxynitrides for Solar Water Splitting: Influence of the Synthesis Conditions

Cited by 44 publications

References 18 publications

Determination of Conduction and Valence Band Electronic Structure of LaTiO_xN_y Thin Film

Determination of Conduction and Valence Band Electronic Structure of LaTiO_xN_y Thin Film

Structural and optical properties of perovskite-type LaTiO2N synthesized using urea or thiourea as co-nitriding agents

Surface structure and anion order of the oxynitride LaTiO₂N

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Perovskite-Type LaTiO2N Oxynitrides for Solar Water Splitting: Influence of the Synthesis Conditions

Cited by 44 publications

References 18 publications

Determination of Conduction and Valence Band Electronic Structure of LaTiOxNy Thin Film

Determination of Conduction and Valence Band Electronic Structure of LaTiOxNy Thin Film

Structural and optical properties of perovskite-type LaTiO2N synthesized using urea or thiourea as co-nitriding agents

Surface structure and anion order of the oxynitride LaTiO2N

Contact Info

Product

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Determination of Conduction and Valence Band Electronic Structure of LaTiO_xN_y Thin Film

Determination of Conduction and Valence Band Electronic Structure of LaTiO_xN_y Thin Film

Surface structure and anion order of the oxynitride LaTiO₂N