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Highly Efficient Photocatalytic Hydrogen Production of Flower-like Cadmium Sulfide Decorated by Histidine.

Wang Q, Lian J, Li J, Wang R, Huang H, Su B, Lei Z - Sci Rep (2015)

Bottom Line: Superior photocatalytic activity relative to that of pure CdS is observed on the flower-like CdS photocatalyst under visible light irradiation, which is nearly 13 times of pure CdS.On the basis of the results from SEM studies and our analysis, a growth mechanism of flower-like CdS is proposed by capturing the shape evolution.The imidazole ring of L-Histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles.

View Article: PubMed Central - PubMed

Affiliation: College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou 730070, China.

ABSTRACT
Morphology-controlled synthesis of CdS can significantly enhance the efficiency of its photocatalytic hydrogen production. In this study, a novel three-dimensional (3D) flower-like CdS is synthesized via a facile template-free hydrothermal process using Cd(NO3)2•4H2O and thiourea as precursors and L-Histidine as a chelating agent. The morphology, crystal phase, and photoelectrochemical performance of the flower-like CdS and pure CdS nanocrystals are carefully investigated via various characterizations. Superior photocatalytic activity relative to that of pure CdS is observed on the flower-like CdS photocatalyst under visible light irradiation, which is nearly 13 times of pure CdS. On the basis of the results from SEM studies and our analysis, a growth mechanism of flower-like CdS is proposed by capturing the shape evolution. The imidazole ring of L-Histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. Furthermore, the photocatalytic contrast experiments illustrate that the as-synthesized flower-like CdS with L-Histidine is more stable than CdS without L-Histidine in the hydrogen generation.

No MeSH data available.


UV-vis absorption spectra (a) and Nitrogen adsorption-desorption isotherms (b) of the samples.
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f6: UV-vis absorption spectra (a) and Nitrogen adsorption-desorption isotherms (b) of the samples.

Mentions: Figure 6a presents UV-vis absorption spectra of the samples. The absorption intensity of pure CdS without L-Histidine starts to increase rapidly at ca. 550 nm. According to the equation, Eg = 1240/λ, the values of the band-gap calculated for CdS is 2.25 eV. The absorption edge in the UV-vis spectrum of the CdS nanoparticle mainly depends on the size of the primary particles22. Thus, the variation in the absorption onset of the CdS nanocrystals indicates the change in size. When the size of the CdS nanocrystals becomes smaller than the exciton radius, a remarkable quantum size effect leads to a size-dependent increase in the band-gap and a blue shift in the absorption onset23. In comparison to the CdS without L-Histidine sample, a little red-shift of the absorption edge for the CdS with L-Histidine sample can be seen. The shift of the absorption edge toward longer wavelengths indicates a little decrease in the bandgap energy of the CdS. This also implies that CdS with L-Histidine has a smaller band gap, and thus it could efficiently separate the photo-generated electron-hole pairs and improve the visible-light photocatalytic H2-production activity.


Highly Efficient Photocatalytic Hydrogen Production of Flower-like Cadmium Sulfide Decorated by Histidine.

Wang Q, Lian J, Li J, Wang R, Huang H, Su B, Lei Z - Sci Rep (2015)

UV-vis absorption spectra (a) and Nitrogen adsorption-desorption isotherms (b) of the samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4559807&req=5

f6: UV-vis absorption spectra (a) and Nitrogen adsorption-desorption isotherms (b) of the samples.
Mentions: Figure 6a presents UV-vis absorption spectra of the samples. The absorption intensity of pure CdS without L-Histidine starts to increase rapidly at ca. 550 nm. According to the equation, Eg = 1240/λ, the values of the band-gap calculated for CdS is 2.25 eV. The absorption edge in the UV-vis spectrum of the CdS nanoparticle mainly depends on the size of the primary particles22. Thus, the variation in the absorption onset of the CdS nanocrystals indicates the change in size. When the size of the CdS nanocrystals becomes smaller than the exciton radius, a remarkable quantum size effect leads to a size-dependent increase in the band-gap and a blue shift in the absorption onset23. In comparison to the CdS without L-Histidine sample, a little red-shift of the absorption edge for the CdS with L-Histidine sample can be seen. The shift of the absorption edge toward longer wavelengths indicates a little decrease in the bandgap energy of the CdS. This also implies that CdS with L-Histidine has a smaller band gap, and thus it could efficiently separate the photo-generated electron-hole pairs and improve the visible-light photocatalytic H2-production activity.

Bottom Line: Superior photocatalytic activity relative to that of pure CdS is observed on the flower-like CdS photocatalyst under visible light irradiation, which is nearly 13 times of pure CdS.On the basis of the results from SEM studies and our analysis, a growth mechanism of flower-like CdS is proposed by capturing the shape evolution.The imidazole ring of L-Histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles.

View Article: PubMed Central - PubMed

Affiliation: College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou 730070, China.

ABSTRACT
Morphology-controlled synthesis of CdS can significantly enhance the efficiency of its photocatalytic hydrogen production. In this study, a novel three-dimensional (3D) flower-like CdS is synthesized via a facile template-free hydrothermal process using Cd(NO3)2•4H2O and thiourea as precursors and L-Histidine as a chelating agent. The morphology, crystal phase, and photoelectrochemical performance of the flower-like CdS and pure CdS nanocrystals are carefully investigated via various characterizations. Superior photocatalytic activity relative to that of pure CdS is observed on the flower-like CdS photocatalyst under visible light irradiation, which is nearly 13 times of pure CdS. On the basis of the results from SEM studies and our analysis, a growth mechanism of flower-like CdS is proposed by capturing the shape evolution. The imidazole ring of L-Histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. Furthermore, the photocatalytic contrast experiments illustrate that the as-synthesized flower-like CdS with L-Histidine is more stable than CdS without L-Histidine in the hydrogen generation.

No MeSH data available.