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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

Nano- or micron-structures obtained from different Pt salts on TiO2 coated substrates subjected to heating at 300°C: (a) H2PtCl6 on Si wafer, (b) Na2Pt(OH)6 on Si wafer and (c) Na2Pt(OH)6 on carbon fibers.
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Figure 3: Nano- or micron-structures obtained from different Pt salts on TiO2 coated substrates subjected to heating at 300°C: (a) H2PtCl6 on Si wafer, (b) Na2Pt(OH)6 on Si wafer and (c) Na2Pt(OH)6 on carbon fibers.

Mentions: After heating the salt solutions at 300°C for 3 h, the SEM image shown in Figure 3a illustrates that the commonly used precursor, H2PtCl6, still remained untransformed and was with nodular or worm-like appearance. For Na2Pt(OH)6 (Figure 3b), all the Pt salt was transformed into Pt NWs in large quantities, with an average diameter of 34 nm and remarkable length of about 6 μm (a superb aspect ratio of up to 200, which is the greatest value reported so far, among Pt NWs synthesized by various template-less and surfactant-free methods), grew vertically on the TiO2 coated Si substrate. No byproducts were found and thus no purificatory procedures are needed. Ultra-long Pt NWs can also be prepared on other substrate materials coated with TiO2. Figure 3c displays Pt NWs grown radially on carbon fibers. The above results manifest that the selection of the precursor was crucial. Given that the melting point of H2PtCl6 is 60°C [20], it can be deduced that H2PtCl6 melted and re-solidified during the thermal treatment. The transformation of Na2Pt(OH)6 into Pt NWs was associated with the relatively lower electronegativity of the OH group (3.02) [21] compared to Cl (3.16), which may cause the metal ions to be reduced easily, thus allow the growth of NWs.


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)

Nano- or micron-structures obtained from different Pt salts on TiO2 coated substrates subjected to heating at 300°C: (a) H2PtCl6 on Si wafer, (b) Na2Pt(OH)6 on Si wafer and (c) Na2Pt(OH)6 on carbon fibers.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Nano- or micron-structures obtained from different Pt salts on TiO2 coated substrates subjected to heating at 300°C: (a) H2PtCl6 on Si wafer, (b) Na2Pt(OH)6 on Si wafer and (c) Na2Pt(OH)6 on carbon fibers.
Mentions: After heating the salt solutions at 300°C for 3 h, the SEM image shown in Figure 3a illustrates that the commonly used precursor, H2PtCl6, still remained untransformed and was with nodular or worm-like appearance. For Na2Pt(OH)6 (Figure 3b), all the Pt salt was transformed into Pt NWs in large quantities, with an average diameter of 34 nm and remarkable length of about 6 μm (a superb aspect ratio of up to 200, which is the greatest value reported so far, among Pt NWs synthesized by various template-less and surfactant-free methods), grew vertically on the TiO2 coated Si substrate. No byproducts were found and thus no purificatory procedures are needed. Ultra-long Pt NWs can also be prepared on other substrate materials coated with TiO2. Figure 3c displays Pt NWs grown radially on carbon fibers. The above results manifest that the selection of the precursor was crucial. Given that the melting point of H2PtCl6 is 60°C [20], it can be deduced that H2PtCl6 melted and re-solidified during the thermal treatment. The transformation of Na2Pt(OH)6 into Pt NWs was associated with the relatively lower electronegativity of the OH group (3.02) [21] compared to Cl (3.16), which may cause the metal ions to be reduced easily, thus allow the growth of NWs.

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