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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.


Transient photocurrent curves (at 0 V versus RHE) of the bulk Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) electrode under (a) UV, (b) visible and (c) near infrared light illumination. (d) Comparison of photocurrent density of various samples under illumination of different light source.
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f3: Transient photocurrent curves (at 0 V versus RHE) of the bulk Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) electrode under (a) UV, (b) visible and (c) near infrared light illumination. (d) Comparison of photocurrent density of various samples under illumination of different light source.

Mentions: Although direct correlations between photocurrent and photocatalytic activity is still absence, close relationship of them are reported and adopted to characterize the property of photocatalysts434445. Generally, larger photocurrent density indicates that more electron and hole pairs are generated under illumination that will take part in the redox reaction occurring on the active site of the surface, thus leading to superior photocatalytic performance. As Bi1−xLaxCuSeO is effective in full solar light region for degradation of azo dye, and improvement of photocatalytic performance due to the introduction of La was confirmed, further investigation was explored using photoelectrochemical (PEC) method to get a deeper understanding of the effect of La doping. PEC measurements were performed on electrochemical work station with standard three electrodes system in 0.5 M Na2SO4 electrolyte and Bi1−xLaxCuSeO ceramic plate (thickness of ca. 360 μm) as working electrode. Pristine and La-doped BiCuSeO photoelectrodes demonstrate similar photocurrent response under full spectrum region (Fig. 3). BiCuSeO photoanode shows photocurrent response as high as 1.74 μA/cm2 and 0.28 μA/cm2 under irradiation of UV and visible light, respectively. Correspondingly, the photoresponse is more intense with photocurrent density of 3.97 μA/cm2 and 0.97 μA/cm2 demonstrated by 8% La-doped specimen. Such enhancement was sustainable during the on-off switch of light illumination. Although no statured current was obtained under the irradiation of NIR light, the photocurrent reveals similar trend in pristine and La-doped BiCuSeO photoanodes. Obviously, La-doped BiCuSeO samples exhibit superior PEC property than pure BiCuSeO under the same incident intensity in the whole solar spectrum. It is also worth noting that the photoelectrodes are made of thick ceramic plate (c.a. 360 μm), thus the photoresponse could be further enhanced by decreasing the thickness or preparing thin film BiCuSeO materials for solar to chemical/electrical conversions.


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)

Transient photocurrent curves (at 0 V versus RHE) of the bulk Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) electrode under (a) UV, (b) visible and (c) near infrared light illumination. (d) Comparison of photocurrent density of various samples under illumination of different light source.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837348&req=5

f3: Transient photocurrent curves (at 0 V versus RHE) of the bulk Bi1−xLaxCuSeO (x = 0, 0.04, 0.08) electrode under (a) UV, (b) visible and (c) near infrared light illumination. (d) Comparison of photocurrent density of various samples under illumination of different light source.
Mentions: Although direct correlations between photocurrent and photocatalytic activity is still absence, close relationship of them are reported and adopted to characterize the property of photocatalysts434445. Generally, larger photocurrent density indicates that more electron and hole pairs are generated under illumination that will take part in the redox reaction occurring on the active site of the surface, thus leading to superior photocatalytic performance. As Bi1−xLaxCuSeO is effective in full solar light region for degradation of azo dye, and improvement of photocatalytic performance due to the introduction of La was confirmed, further investigation was explored using photoelectrochemical (PEC) method to get a deeper understanding of the effect of La doping. PEC measurements were performed on electrochemical work station with standard three electrodes system in 0.5 M Na2SO4 electrolyte and Bi1−xLaxCuSeO ceramic plate (thickness of ca. 360 μm) as working electrode. Pristine and La-doped BiCuSeO photoelectrodes demonstrate similar photocurrent response under full spectrum region (Fig. 3). BiCuSeO photoanode shows photocurrent response as high as 1.74 μA/cm2 and 0.28 μA/cm2 under irradiation of UV and visible light, respectively. Correspondingly, the photoresponse is more intense with photocurrent density of 3.97 μA/cm2 and 0.97 μA/cm2 demonstrated by 8% La-doped specimen. Such enhancement was sustainable during the on-off switch of light illumination. Although no statured current was obtained under the irradiation of NIR light, the photocurrent reveals similar trend in pristine and La-doped BiCuSeO photoanodes. Obviously, La-doped BiCuSeO samples exhibit superior PEC property than pure BiCuSeO under the same incident intensity in the whole solar spectrum. It is also worth noting that the photoelectrodes are made of thick ceramic plate (c.a. 360 μm), thus the photoresponse could be further enhanced by decreasing the thickness or preparing thin film BiCuSeO materials for solar to chemical/electrical conversions.

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.