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Bi(1-x)La(x)CuSeO as New Tunable Full Solar Light Active Photocatalysts.

Wang H, Li S, Liu Y, Ding J, Lin YH, Xu H, Xu B, Nan CW - Sci Rep (2016)

Bottom Line: However, efficiently harvesting solar energy for photocatalysis remains a pressing challenge, and the charge kinetics and mechanism of the photocatalytic process is far from being well understood.Our measurements and density-functional-theory calculations reveal that the effective mass and mobility of the carriers in BiCuSeO can be tuned by the La-doping, which are responsible for the tunable photocatalytic activity.Our findings may offer new perspectives for understanding the mechanism of photocatalysis through modulating the charge mobility and the effective mass of carriers and provide a guidance for designing efficient photocatalyts.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.

ABSTRACT
Photocatalysis is attracting enormous interest driven by the great promise of addressing current energy and environmental crises by converting solar light directly into chemical energy. However, efficiently harvesting solar energy for photocatalysis remains a pressing challenge, and the charge kinetics and mechanism of the photocatalytic process is far from being well understood. Here we report a new full solar spectrum driven photocatalyst in the system of a layered oxyselenide BiCuSeO with good photocatalytic activity for degradation of organic pollutants and chemical stability under light irradiation, and the photocatalytic performance of BiCuSeO can be further improved by band gap engineering with introduction of La. Our measurements and density-functional-theory calculations reveal that the effective mass and mobility of the carriers in BiCuSeO can be tuned by the La-doping, which are responsible for the tunable photocatalytic activity. Our findings may offer new perspectives for understanding the mechanism of photocatalysis through modulating the charge mobility and the effective mass of carriers and provide a guidance for designing efficient photocatalyts.

No MeSH data available.


Related in: MedlinePlus

(a) The crystalline structure of La-doped BiCuSeO used in DFT calculations. (b) UV-Vis-NIR absorbance spectra of Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) powder samples. Insert shows the variation of bandgaps with different La doping content estimated by Kubelka-Munk transformation.
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f1: (a) The crystalline structure of La-doped BiCuSeO used in DFT calculations. (b) UV-Vis-NIR absorbance spectra of Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) powder samples. Insert shows the variation of bandgaps with different La doping content estimated by Kubelka-Munk transformation.

Mentions: Oxyselenide compound BiCuSeO has been extensively investigated as a promising oxide-based thermoelectric material in the moderate temperature range in recent years triggered by Zhao’s work in 201032. A variety of methods have been employed to tune the electrical and thermal properties, including doping to optimize charge carrier concentration3334353637 and tune the transport properties of carriers38, introducing Cu deficiencies39 and band gap tuning to enhance electrical conductivity40, and texturing to improve the mobility of carriers41. The crystal structure of BiCuSeO belongs to the ZrSiCuAs-type structure with the tetragonal P4/nmm space group that constitutes the alternately stacked (Bi2O2)2+ insulating layers and (Cu2Se2)2− conductive layers along the c-axis of the tetragonal cell, as illustrated in Fig. 1a. Motivated by their unique layered structure, favorable transport properties of carriers and tunable narrow band gap, Bi1−xLaxCuSeO samples with different compositions (x = 0, 0.04 and 0.08) in powdered form were prepared (see Methods) to test their potential utilization as photocatalysts. Powder X-ray diffraction (Fig. S1, Supplementary Information) reveals that all diffraction peaks can be well indexed to the pure phase of BiCuSeO (JCPDS no. 45–0296), without impurity peaks appearing in all as-prepared samples. The lattice constants a and c increase with increasing La doping content from 0 to 0.08, indicating that La3+ is successfully incorporated into the BiCuSeO lattice. The scanning electron microscopy (SEM) image (Fig. S2a, Supplementary Information) demonstrates that the crushed BiCuSeO powders are consist of irregular shaped particles with dimensions from tens to hundreds of nanometers. The polycrystalline nature of the BiCuSeO sample was further confirmed by high resolution transmission electron microscopy (HRTEM). Agglomerated nanocrystals with grain sizes ranging from 5 to 10 nm can be observed to form polycrystalline particles with amorphous-like boundary (Fig. S2b, Supplementary Information). However, individual well-crystallized nanocrystals were also noticed, as exemplified in Fig. S2c in the Supplementary information.


Bi(1-x)La(x)CuSeO as New Tunable Full Solar Light Active Photocatalysts.

Wang H, Li S, Liu Y, Ding J, Lin YH, Xu H, Xu B, Nan CW - Sci Rep (2016)

(a) The crystalline structure of La-doped BiCuSeO used in DFT calculations. (b) UV-Vis-NIR absorbance spectra of Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) powder samples. Insert shows the variation of bandgaps with different La doping content estimated by Kubelka-Munk transformation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4837348&req=5

f1: (a) The crystalline structure of La-doped BiCuSeO used in DFT calculations. (b) UV-Vis-NIR absorbance spectra of Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) powder samples. Insert shows the variation of bandgaps with different La doping content estimated by Kubelka-Munk transformation.
Mentions: Oxyselenide compound BiCuSeO has been extensively investigated as a promising oxide-based thermoelectric material in the moderate temperature range in recent years triggered by Zhao’s work in 201032. A variety of methods have been employed to tune the electrical and thermal properties, including doping to optimize charge carrier concentration3334353637 and tune the transport properties of carriers38, introducing Cu deficiencies39 and band gap tuning to enhance electrical conductivity40, and texturing to improve the mobility of carriers41. The crystal structure of BiCuSeO belongs to the ZrSiCuAs-type structure with the tetragonal P4/nmm space group that constitutes the alternately stacked (Bi2O2)2+ insulating layers and (Cu2Se2)2− conductive layers along the c-axis of the tetragonal cell, as illustrated in Fig. 1a. Motivated by their unique layered structure, favorable transport properties of carriers and tunable narrow band gap, Bi1−xLaxCuSeO samples with different compositions (x = 0, 0.04 and 0.08) in powdered form were prepared (see Methods) to test their potential utilization as photocatalysts. Powder X-ray diffraction (Fig. S1, Supplementary Information) reveals that all diffraction peaks can be well indexed to the pure phase of BiCuSeO (JCPDS no. 45–0296), without impurity peaks appearing in all as-prepared samples. The lattice constants a and c increase with increasing La doping content from 0 to 0.08, indicating that La3+ is successfully incorporated into the BiCuSeO lattice. The scanning electron microscopy (SEM) image (Fig. S2a, Supplementary Information) demonstrates that the crushed BiCuSeO powders are consist of irregular shaped particles with dimensions from tens to hundreds of nanometers. The polycrystalline nature of the BiCuSeO sample was further confirmed by high resolution transmission electron microscopy (HRTEM). Agglomerated nanocrystals with grain sizes ranging from 5 to 10 nm can be observed to form polycrystalline particles with amorphous-like boundary (Fig. S2b, Supplementary Information). However, individual well-crystallized nanocrystals were also noticed, as exemplified in Fig. S2c in the Supplementary information.

Bottom Line: However, efficiently harvesting solar energy for photocatalysis remains a pressing challenge, and the charge kinetics and mechanism of the photocatalytic process is far from being well understood.Our measurements and density-functional-theory calculations reveal that the effective mass and mobility of the carriers in BiCuSeO can be tuned by the La-doping, which are responsible for the tunable photocatalytic activity.Our findings may offer new perspectives for understanding the mechanism of photocatalysis through modulating the charge mobility and the effective mass of carriers and provide a guidance for designing efficient photocatalyts.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.

ABSTRACT
Photocatalysis is attracting enormous interest driven by the great promise of addressing current energy and environmental crises by converting solar light directly into chemical energy. However, efficiently harvesting solar energy for photocatalysis remains a pressing challenge, and the charge kinetics and mechanism of the photocatalytic process is far from being well understood. Here we report a new full solar spectrum driven photocatalyst in the system of a layered oxyselenide BiCuSeO with good photocatalytic activity for degradation of organic pollutants and chemical stability under light irradiation, and the photocatalytic performance of BiCuSeO can be further improved by band gap engineering with introduction of La. Our measurements and density-functional-theory calculations reveal that the effective mass and mobility of the carriers in BiCuSeO can be tuned by the La-doping, which are responsible for the tunable photocatalytic activity. Our findings may offer new perspectives for understanding the mechanism of photocatalysis through modulating the charge mobility and the effective mass of carriers and provide a guidance for designing efficient photocatalyts.

No MeSH data available.


Related in: MedlinePlus