Crystal growth and conductivity investigations on BiVO4 single crystals

Hoffart, L.; Heider, U.; Huggins, Robert A.; Witschel, W.; Jooss, R.; Lentz, A.

doi:10.1007/bf02375866

Cited by 24 publications

(22 citation statements)

References 14 publications

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“…On the other hand, the properties of BiVO 4 are strongly dependent on its morphology and microstructure [24,26,[28][29][30][31][32][33]. According to previous reports, BiVO 4 appears in three main crystalline phases: monoclinic scheelite, tetragonal zircon, and tetragonal scheelite [34][35][36]. Among the above three crystal phase, monoclinic BiVO 4 is the best visible-light-driven photocatalyst for the degradation of 2 International Journal of Photoenergy organic pollutants and O 2 production from water splitting due to the transition from a valence band formed by Bi 6s or a hybrid orbital of Bi 6s and O 2p to a conduction band of V3d and its narrow band gap (ca.…”

Section: Introductionmentioning

confidence: 99%

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

Cheng

Wang

Shi

et al. 2012

International Journal of Photoenergy

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Monoclinic-phase BiVO 4 hollow microspheres with diameters of about 2-4 μm have been successfully fabricated in high yield by a one-pot template-free hydrothermal route. The reaction duration and urea concentration are shown to play important roles in the formation of the BiVO 4 hollow microspheres. X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption isotherms, fourier transform infrared spectrometry, and UV-visible diffuse reflectance spectroscopy are used to characterize the products. The results show that all the as-prepared BiVO 4 samples have monoclinic phase structure and exhibit good crystallinity. A formation mechanism for the BiVO 4 hollow spherical structure via a localized Ostwald ripening is proposed based on the experimental observations. In addition, studies of the photocatalytic properties by exposure to visible light irradiation demonstrate that the as-obtained BiVO 4 hollow spheres show potential photocatalytic application. Hydroxyl radicals ( • OH) are not detected on the surface of visible-light-illuminated BiVO 4 by the photoluminescence technique, suggesting that • OH is not the dominant photooxidant and photogenerated hole could directly take part in photocatalytic reaction. The prepared BiVO 4 hollow spheres are also of great interest in pigment, catalysis, separation technology, biomedical engineering, and nanotechnology.

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Section: Introductionmentioning

confidence: 99%

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

Cheng

Wang

Shi

et al. 2012

International Journal of Photoenergy

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“…Given that the c-axis is reported to be the direction of highest resistivity (i.e., lowest mobility) in BVO crystals, 17,71 we expect c-axis texture in nanoporous BVO films to result in better hole transport but worse electron transport compared to untextured films. Substantially better hole collection due to less c-axis character in the hole transit path could account for the higher photocurrent of Mo/T films, but only if the lower electron mobility within the BVO grains has an insignificant negative impact on the electron collection efficiency.…”

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confidence: 99%

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Nair

Perkins

Lin

et al. 2016

Energy Environ. Sci.

155

106

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We have developed a simple spin coating method to make high-quality nanoporous photoelectrodes of monoclinic BiVO 4 and studied the ability of these electrodes to transport photogenerated carriers to oxidize sulfite and water. Samples containing molybdenum and featuring [001] out-of-plane crystallographic texture show a photocurrent and external quantum efficiency (EQE) for sulfite oxidation as high as 3.1 mA cm À2 and 60%, respectively, at 1.23 V versus reversible hydrogen electrode. By using an optical model of the electrode stack to accurately determine the fraction of electrode absorptance due to the BiVO 4 active layer, we estimate that on average 70 AE 5% of all photogenerated carriers escape recombination. A comparison of internal quantum efficiency as a function of film processing, illumination direction, and film thickness shows that electron transport is efficient and hole transport limits the photocurrent (hole diffusion length o40 nm). We find that Mo addition primarily improves electron transport and texturing mostly improves hole transport. Mo enhances electron transport by thinning the surface depletion layer or passivating traps and recombination centers at grain boundaries and interfaces, while improved hole transport in textured films may result from more efficient lateral hole extraction due to the texturing itself or the reduced density of deep gap states observed in photoemission measurements.Photoemission data also reveal that the films have bismuth-rich, vanadium-and oxygen-deficient surface layers, while ion scattering spectroscopy indicates a Bi-V-O surface termination. Without added catalysts, the plain BiVO 4 electrodes oxidized water with an initial photocurrent and peak EQE of 1.7 mA cm À2 and 30%, respectively, which equates to a hole transfer efficiency to water of 464% at 1.23 V. The electrodes quickly photocorrode during water oxidation but show good stability during sulfite oxidation and indefinite stability in the dark. By improving the hole transport efficiency and coating these nanoporous BiVO 4 films with an appropriate protective layer and oxygen evolution catalyst, it should be possible to achieve highly efficient and stable water oxidation at a practical pH.

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“…Scheelites exist in a wide range of compositions and have a rather open crystal structure, which can be simply thought of as a modification of the fluorite structure with an ordered arrangement of the two cations. 30 Bi 0.55 MoO 4 belongs to the scheelite structure of CaWO 4 , isomorphic with Eu 2 ĲWO 4 ) 3 and Nd 2 ĲMoO 4 ) 3 . For Eu 2 ĲWO 4 ) 3 , the crystal structure can be viewed as a stacking up of the Ca 2+ and WO 4 2− ions in scheelite, where every three Ca 2+ ions have been replaced with two Eu 3+ ions and a vacancy.…”

Section: Resultsmentioning

confidence: 99%

Effect of high bismuth deficiency on structure and oxide ion conductivity of a Bi_0.55MoO₄ single crystal

Zhang

Cong

et al. 2015

CrystEngComm

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Crystal growth and conductivity investigations on BiVO4 single crystals

Cited by 24 publications

References 14 publications

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Effect of high bismuth deficiency on structure and oxide ion conductivity of a Bi_0.55MoO₄ single crystal

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Crystal growth and conductivity investigations on BiVO4 single crystals

Cited by 24 publications

References 14 publications

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

Textured nanoporous Mo:BiVO4 photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Effect of high bismuth deficiency on structure and oxide ion conductivity of a Bi0.55MoO4 single crystal

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Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Effect of high bismuth deficiency on structure and oxide ion conductivity of a Bi_0.55MoO₄ single crystal