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Direct growth of ultra-long platinum nanolawns on a semiconductor photocatalyst.

Shen YL, Chen SY, Song JM, Chin TK, Lin CH, Chen IG - Nanoscale Res Lett (2011)

Bottom Line: A template- and surfactant-free process, thermally assisted photoreduction, is developed to prepare vertically grown ultra-long Pt nanowires (NWs) (about 30-40 nm in diameter, 5-6 μm in length, and up to 80 NWs/100 μm2 in the wire density) on TiO2 coated substrates, including Si wafers and carbon fibers, with the assistance of the photocatalytic ability and semiconductor characteristics of TiO2.TEM analytical results suggest that the Pt NWs are single-crystalline with a preferred ⟨111⟩ growth direction.The interactions between the ions and the electrons in the Pt/TiO2 junction are discussed in this study.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, National Dong Hwa University, Hualien 974, Taiwan. samsong@mail.ndhu.edu.tw.

ABSTRACT
A template- and surfactant-free process, thermally assisted photoreduction, is developed to prepare vertically grown ultra-long Pt nanowires (NWs) (about 30-40 nm in diameter, 5-6 μm in length, and up to 80 NWs/100 μm2 in the wire density) on TiO2 coated substrates, including Si wafers and carbon fibers, with the assistance of the photocatalytic ability and semiconductor characteristics of TiO2. A remarkable aspect ratio of up to 200 can be achieved. TEM analytical results suggest that the Pt NWs are single-crystalline with a preferred 〈111〉 growth direction. The precursor adopted and the heat treatment conditions are crucial for the yield of NWs. The photoelectrons supplied by TiO2 gives rise to the formation of nano-sized Pt nuclei from salt melt or solution. The subsequent growth of NWs is supported by the thermal electrons which also generated from TiO2 during the post thermal treatment. The interactions between the ions and the electrons in the Pt/TiO2 junction are discussed in this study.

No MeSH data available.


Related in: MedlinePlus

Histograms of the quantitative data of Pt NWs under different growth conditions: (a) diameter, (b) wire length and (c) wire density (the yield of NWs).
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Figure 6: Histograms of the quantitative data of Pt NWs under different growth conditions: (a) diameter, (b) wire length and (c) wire density (the yield of NWs).

Mentions: To clarify how the state of the precursor affects the yield of NWs, Na2Pt(OH)6 powders and aqueous solution were placed or dropped on the TiO2 coated Si wafers, respectively, and isothermally treated at chosen temperatures for 3 h in air by an IR furnace. According to the melting point of Na2Pt(OH)6, 150°C [20], the thermal treatment was held at 140°C to keep the salt in solid state or 160°C to turn it into liquid. The SEM images in Figure 5 show the morphologies of the samples after the TAP routes. For the solution samples after being thermal-treated at 140°C for 3 h (Figure 5a), chunky Na2Pt(OH)6 nodules and very few Pt NWs located in between them could be observed. Interestingly, when the holding temperature was raised to 160°C, the Pt salt solution was transformed into a plenty of Pt NWs with the average diameter of 40.9 nm and length of about 5.2 μm (Figures 5b and 6a,b), which were slightly shorter and thicker than those synthesized at 300°C. Similar results were observed if the aqueous solution was replaced by powders. As illustrated in Figure 5c, the powders of Na2Pt(OH)6 remained without forming any NWs subsequent to the post thermal treatment at 140°C. Remarkably, after isothermal heating at 160°C, Na2Pt(OH)6 powders were transformed to Pt nanolawns, with average wire diameter and length of 44.6 nm and 5.8 μm, respectively (Figures 5d and 6a,b).


Direct growth of ultra-long platinum nanolawns on a semiconductor photocatalyst.

Shen YL, Chen SY, Song JM, Chin TK, Lin CH, Chen IG - Nanoscale Res Lett (2011)

Histograms of the quantitative data of Pt NWs under different growth conditions: (a) diameter, (b) wire length and (c) wire density (the yield of NWs).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211474&req=5

Figure 6: Histograms of the quantitative data of Pt NWs under different growth conditions: (a) diameter, (b) wire length and (c) wire density (the yield of NWs).
Mentions: To clarify how the state of the precursor affects the yield of NWs, Na2Pt(OH)6 powders and aqueous solution were placed or dropped on the TiO2 coated Si wafers, respectively, and isothermally treated at chosen temperatures for 3 h in air by an IR furnace. According to the melting point of Na2Pt(OH)6, 150°C [20], the thermal treatment was held at 140°C to keep the salt in solid state or 160°C to turn it into liquid. The SEM images in Figure 5 show the morphologies of the samples after the TAP routes. For the solution samples after being thermal-treated at 140°C for 3 h (Figure 5a), chunky Na2Pt(OH)6 nodules and very few Pt NWs located in between them could be observed. Interestingly, when the holding temperature was raised to 160°C, the Pt salt solution was transformed into a plenty of Pt NWs with the average diameter of 40.9 nm and length of about 5.2 μm (Figures 5b and 6a,b), which were slightly shorter and thicker than those synthesized at 300°C. Similar results were observed if the aqueous solution was replaced by powders. As illustrated in Figure 5c, the powders of Na2Pt(OH)6 remained without forming any NWs subsequent to the post thermal treatment at 140°C. Remarkably, after isothermal heating at 160°C, Na2Pt(OH)6 powders were transformed to Pt nanolawns, with average wire diameter and length of 44.6 nm and 5.8 μm, respectively (Figures 5d and 6a,b).

Bottom Line: A template- and surfactant-free process, thermally assisted photoreduction, is developed to prepare vertically grown ultra-long Pt nanowires (NWs) (about 30-40 nm in diameter, 5-6 μm in length, and up to 80 NWs/100 μm2 in the wire density) on TiO2 coated substrates, including Si wafers and carbon fibers, with the assistance of the photocatalytic ability and semiconductor characteristics of TiO2.TEM analytical results suggest that the Pt NWs are single-crystalline with a preferred ⟨111⟩ growth direction.The interactions between the ions and the electrons in the Pt/TiO2 junction are discussed in this study.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, National Dong Hwa University, Hualien 974, Taiwan. samsong@mail.ndhu.edu.tw.

ABSTRACT
A template- and surfactant-free process, thermally assisted photoreduction, is developed to prepare vertically grown ultra-long Pt nanowires (NWs) (about 30-40 nm in diameter, 5-6 μm in length, and up to 80 NWs/100 μm2 in the wire density) on TiO2 coated substrates, including Si wafers and carbon fibers, with the assistance of the photocatalytic ability and semiconductor characteristics of TiO2. A remarkable aspect ratio of up to 200 can be achieved. TEM analytical results suggest that the Pt NWs are single-crystalline with a preferred 〈111〉 growth direction. The precursor adopted and the heat treatment conditions are crucial for the yield of NWs. The photoelectrons supplied by TiO2 gives rise to the formation of nano-sized Pt nuclei from salt melt or solution. The subsequent growth of NWs is supported by the thermal electrons which also generated from TiO2 during the post thermal treatment. The interactions between the ions and the electrons in the Pt/TiO2 junction are discussed in this study.

No MeSH data available.


Related in: MedlinePlus