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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.


SEM images of CdS prepared without L-Histidine (a–c) and with L-Histidine (d–f), and SEM image of CdS prepared with L-Histidine after 5 h of reaction under the visible-light irradiation (g).
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f2: SEM images of CdS prepared without L-Histidine (a–c) and with L-Histidine (d–f), and SEM image of CdS prepared with L-Histidine after 5 h of reaction under the visible-light irradiation (g).

Mentions: The morphology of the as-synthesized 3D CdS nanoarchitectures was examined by SEM and TEM. Figure 2(a–c) show SEM images of CdS prepared without L-Histidine, showing irregularity of dendritic architecture. Figure 2d,e show that CdS has flower-like morphology by synthesizing with the assistance of L-Histidine. Figure 2f gives out an amplifying representative flower-like morphology. It is interesting to note that the flower-like CdS nanostructures consisted of CdS nanorods, which protrude from the root of the flower-like CdS. Figure 2g proves that the morphology of CdS flower-like does not change after 5 h of reaction under the visible-light irradiation, indicating that the flower-like morphology is stable during the visible-light irradiation. In order to check the influence of L-Histidine on the morphology of CdS, different concentrations of the reagents (Cd precursor and histidine) are designed, as shown in Figure S1, the ratio of Cd precursor to histidine is 10:1, 10:2, 10:3, 10:5, and 10:10, respectively. Figure S1c presents a flower-like CdS, in which the ratio of Cd precursor to L-histidine is 10:3. The morphologies in Figure S1a and Figure S1b are similar to the one in Figure S1c, but CdS in Figure S1a and Figure S1b aggregates and has poorer crystallinity. Figure S1d and Figure S1e indicate that CdS has cauliflower-like structure when the ratio between Cd precursor and L-histidine is 10:5 or 10:10. The morphologies of products are controlled by the rates of nucleation and crystal growth. When the rate of crystalline nucleation is greater than that of crystal growth, the particle sizes will be small and the particle has low aggregation. Contrarily, rapid crystal growth will generate large particle sizes and heavy aggregation. By using the high concentration of L-histidine, it could accelerate the crystal growth to be faster than crystalline nucleation. Thus the concentration of L-histidine influences the morphology of CdS. So the optimal ratio of Cd precursor and histidine is10:3.


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)

SEM images of CdS prepared without L-Histidine (a–c) and with L-Histidine (d–f), and SEM image of CdS prepared with L-Histidine after 5 h of reaction under the visible-light irradiation (g).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: SEM images of CdS prepared without L-Histidine (a–c) and with L-Histidine (d–f), and SEM image of CdS prepared with L-Histidine after 5 h of reaction under the visible-light irradiation (g).
Mentions: The morphology of the as-synthesized 3D CdS nanoarchitectures was examined by SEM and TEM. Figure 2(a–c) show SEM images of CdS prepared without L-Histidine, showing irregularity of dendritic architecture. Figure 2d,e show that CdS has flower-like morphology by synthesizing with the assistance of L-Histidine. Figure 2f gives out an amplifying representative flower-like morphology. It is interesting to note that the flower-like CdS nanostructures consisted of CdS nanorods, which protrude from the root of the flower-like CdS. Figure 2g proves that the morphology of CdS flower-like does not change after 5 h of reaction under the visible-light irradiation, indicating that the flower-like morphology is stable during the visible-light irradiation. In order to check the influence of L-Histidine on the morphology of CdS, different concentrations of the reagents (Cd precursor and histidine) are designed, as shown in Figure S1, the ratio of Cd precursor to histidine is 10:1, 10:2, 10:3, 10:5, and 10:10, respectively. Figure S1c presents a flower-like CdS, in which the ratio of Cd precursor to L-histidine is 10:3. The morphologies in Figure S1a and Figure S1b are similar to the one in Figure S1c, but CdS in Figure S1a and Figure S1b aggregates and has poorer crystallinity. Figure S1d and Figure S1e indicate that CdS has cauliflower-like structure when the ratio between Cd precursor and L-histidine is 10:5 or 10:10. The morphologies of products are controlled by the rates of nucleation and crystal growth. When the rate of crystalline nucleation is greater than that of crystal growth, the particle sizes will be small and the particle has low aggregation. Contrarily, rapid crystal growth will generate large particle sizes and heavy aggregation. By using the high concentration of L-histidine, it could accelerate the crystal growth to be faster than crystalline nucleation. Thus the concentration of L-histidine influences the morphology of CdS. So the optimal ratio of Cd precursor and histidine is10:3.

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.