Effects of flux treatment on morphology of single-crystalline BaNbO<sub>2</sub>N particles

Kodera, Masanori; Katayama, Masao; Hisatomi, Takashi; Minegishi, Tsutomu; Domen, Kazunari

doi:10.1039/c5ce02335a

Cited by 19 publications

(16 citation statements)

References 21 publications

(21 reference statements)

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“…These results are similar to the crystallinity trend observed in the case of the BaNbO 3 when varying the Nb amount, implying that the crystallinity of BaNbO 3 determines that of BaNbO 2 N. The improved crystallinity of BaNbO 2 N was comparable to that of highly crystalline BaNbO 2 N obtained by a flux-assisted synthesis in our previous study. 10,13 Therefore, it is clear that synthesis using perovskite-type BaNbO 3 is an effective means of obtaining highly crystalline BaNbO 2 N by solid-state reaction. The structural transition of high crystalline BaNbO 3 (2.0Nb) during nitridation over 20 h was investigated, and the results are shown in Figure 4.…”

Section: Resultsmentioning

confidence: 99%

“…In these compounds, the substitution of Nb at B sites lowers the band gap energy to well below that of Ta, owing to the relatively high electronegativity of Nb. SrNbO 2 N and BaNbO 2 N photocatalysts exhibit the longest light absorption edges of 700 and 740 nm, respectively, suggesting that the use of these materials may result in high STH conversion efficiencies. − …”

Section: Introductionmentioning

confidence: 99%

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Photoelectrochemical Water Splitting on Particulate ANbO₂N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO₃

et al. 2016

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Perovskite-type Nb-based oxynitrides (ANbO 2 N, A = Ba, Sr) exhibiting absorption of long light wavelengths up to (A = Sr) or even above 700 nm (A = Ba) were synthesized from stoichiometric perovskite-type oxides (ANbO 3 ) by a typical thermal ammonolysis method. The preparation of BaNbO 2 N using BaNbO 3 having an identical cubic-perovskite-type structure was demonstrated to effectively improve the surface and bulk crystallinity of the oxynitride because of the absence of a structural transition during nitridation and the stoichiometric 1:1 Ba/Nb ratio between the oxides and oxynitrides. The resulting BaNbO 2 N photoanode exhibited photoelectrochemical water oxidation activity with a current density of 0.85 mA cm −2 at 1.23 V RHE and a faradaic efficiency close to unity under simulated solar illumination (AM 1.5G). The associated incident photon-to-current efficiency in the range of 740−480 nm showed that BaNbO 2 N produces a photoanodic current at 740 nm, the longest response wavelength ever reported for a photoanode based on an (oxy)nitride.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Water Splitting on Particulate ANbO₂N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO₃

et al. 2016

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“…In addition, Kodera et al. reported that BaNbO 2 N crystals with different morphologies and crystallinities can be prepared using a range of alkali halide fluxes, and they demonstrated that the types of cations present in the flux play an important role in determining the shapes of the resulting BaNbO 2 N crystals . It is noted that the morphology and crystallinity of crystals are also determined by the synthetic conditions employed, as these can influence the solubility of the solutes; examples include the precursor-to-flux molar ratio, the operating temperature, and the nitridation time. − The optimization of these conditions along with the flux is therefore of particular importance.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Single-Crystalline BaTaO₂N from Chloride Fluxes for Photocatalytic H₂ Evolution under Visible Light

Luo

Wang

Suzuki

et al. 2019

Crystal Growth & Design

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BaTaO 2 N is an important oxynitride photocatalyst for the splitting of water under visible light. However, the preparation of BaTaO 2 N crystals with low defect densities and high crystallinities is challenging via ammonolysis at high temperatures. Thus, we herein report the preparation of BaTaO 2 N crystals using an NH 3 -assisted flux method. We initially studied the effects of the flux type (RbCl, CsCl, and BaCl 2 •2H 2 O) on the morphology, crystallinity, and photocatalytic performance of the BaTaO 2 N crystals. It was found that the BaTaO 2 N crystals grown using a RbCl flux exhibited a significantly higher photocatalytic H 2 evolution rate than those grown using the other two fluxes. In particular, the observed activity was almost twice as high as that reported over BaTaO 2 N crystals grown using a KCl flux. Such an excellent activity could be attributed to the lower defect density and higher crystallinity, which were confirmed by UV−vis diffuse reflectance spectroscopy and composition analysis. Subsequently, the effects of the source ratio, solute concentration, reaction temperature, and time on the crystallinity and morphology of the BaTaO 2 N crystals grown using a RbCl flux were studied systematically to gain insight into the BaTaO 2 N crystal growth mechanism.

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“…In particular, the skeletal and edgy morphology has higher CoOx catalyst dispersion on the LaTiO 2 N electrode contained unsaturated bonds, thereby improving the photocatalytic O 2 evolution. Moreover, Kodera et al demonstrated that flux treatment on BaNbO 2 N photoelectrodes greatly influenced the morphological natures [83]. Prior to flux action, the BaNbO 2 N morphological features were uncertain, with an accumulation of particle sizes varied from a few 10' s nm to 100 s nm.…”

Section: (Oxy)nitrides Based Materialsmentioning

confidence: 99%

Recent Developments in the Use of Heterogeneous Semiconductor Photocatalyst Based Materials for a Visible-Light-Induced Water-Splitting System—A Brief Review

et al. 2021

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Visible-light-driven photoelectrochemical (PEC) and photocatalytic water splitting systems featuring heterogeneous semiconductor photocatalysts (oxynitrides, oxysulfides, organophotocatalysts) signify an environmentally friendly and promising approach for the manufacturing of renewable hydrogen fuel. Semiconducting electrode materials as the main constituents in the PEC water splitting system have substantial effects on the device’s solar-to-hydrogen (STH) conversion efficiency. Given the complication of the photocatalysis and photoelectrolysis methods, it is indispensable to include the different electrocatalytic materials for advancing visible-light-driven water splitting, considered a difficult challenge. Heterogeneous semiconductor-based materials with narrower bandgaps (2.5 to 1.9 eV), equivalent to the theoretical STH efficiencies ranging from 9.3% to 20.9%, are recognized as new types of photoabsorbents to engage as photoelectrodes for PEC water oxidation and have fascinated much consideration. Herein, we spotlight mainly on heterogenous semiconductor-based photoanode materials for PEC water splitting. Different heterogeneous photocatalysts based materials are emphasized in different groups, such as oxynitrides, oxysulfides, and organic solids. Lastly, the design approach and future developments regarding heterogeneous photocatalysts oxide electrodes for PEC applications and photocatalytic applications are also discussed.

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Effects of flux treatment on morphology of single-crystalline BaNbO₂N particles

Abstract: Single crystalline BaNbO2N particles with crystal habits were obtained by appropriate flux treatments.

Cited by 19 publications

References 21 publications

Photoelectrochemical Water Splitting on Particulate ANbO₂N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO₃

Photoelectrochemical Water Splitting on Particulate ANbO₂N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO₃

Fabrication of Single-Crystalline BaTaO₂N from Chloride Fluxes for Photocatalytic H₂ Evolution under Visible Light

Recent Developments in the Use of Heterogeneous Semiconductor Photocatalyst Based Materials for a Visible-Light-Induced Water-Splitting System—A Brief Review

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Effects of flux treatment on morphology of single-crystalline BaNbO2N particles

Abstract: Single crystalline BaNbO2N particles with crystal habits were obtained by appropriate flux treatments.

Cited by 19 publications

References 21 publications

Photoelectrochemical Water Splitting on Particulate ANbO2N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO3

Photoelectrochemical Water Splitting on Particulate ANbO2N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO3

Fabrication of Single-Crystalline BaTaO2N from Chloride Fluxes for Photocatalytic H2 Evolution under Visible Light

Recent Developments in the Use of Heterogeneous Semiconductor Photocatalyst Based Materials for a Visible-Light-Induced Water-Splitting System—A Brief Review

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Effects of flux treatment on morphology of single-crystalline BaNbO₂N particles

Photoelectrochemical Water Splitting on Particulate ANbO₂N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO₃

Photoelectrochemical Water Splitting on Particulate ANbO₂N (A = Ba, Sr) Photoanodes Prepared from Perovskite-Type ANbO₃

Fabrication of Single-Crystalline BaTaO₂N from Chloride Fluxes for Photocatalytic H₂ Evolution under Visible Light