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Structural Evolution of Chemically-Driven RuO2 Nanowires and 3-Dimensional Design for Photo-Catalytic Applications.

Park J, Lee JW, Ye BU, Chun SH, Joo SH, Park H, Lee H, Jeong HY, Kim MH, Baik JM - Sci Rep (2015)

Bottom Line: Growth then proceeds by Ru diffusion to the nanoparticles, followed by the diffusion to the growing surface of the nanowire in oxygen ambient, supported by the nucleation theory.The RuO2 branched Au-TiO2 nanowire arrays shows a remarkable enhancement in the photocurrent density by approximately 60% and 200%, in the UV-visible and Visible region, respectively, compared with pristine TiO2 nanowires.Furthermore, there is no significant decrease in the device's photoconductance with UV-visible illumination during 1 day, making it possible to produce oxygen gas without the loss of the photoactvity.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, KIST-UNIST-Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea.

ABSTRACT
Growth mechanism of chemically-driven RuO2 nanowires is explored and used to fabricate three-dimensional RuO2 branched Au-TiO2 nanowire electrodes for the photostable solar water oxidation. For the real time structural evolution during the nanowire growth, the amorphous RuO2 precursors (Ru(OH)3 · H2O) are heated at 180 (°)C, producing the RuO2 nanoparticles with the tetragonal crystallographic structure and Ru enriched amorphous phases, observed through the in-situ synchrotron x-ray diffraction and the high-resolution transmission electron microscope images. Growth then proceeds by Ru diffusion to the nanoparticles, followed by the diffusion to the growing surface of the nanowire in oxygen ambient, supported by the nucleation theory. The RuO2 branched Au-TiO2 nanowire arrays shows a remarkable enhancement in the photocurrent density by approximately 60% and 200%, in the UV-visible and Visible region, respectively, compared with pristine TiO2 nanowires. Furthermore, there is no significant decrease in the device's photoconductance with UV-visible illumination during 1 day, making it possible to produce oxygen gas without the loss of the photoactvity.

No MeSH data available.


Related in: MedlinePlus

(a) SEM images and (b) the corresponding XRD patterns (● : (110), ○ : (101), ■ : (200), and □ : (211)) of RuO2 nanowires as a function of temperature (scale bar, 100 nm). The peak at 33.2 ° is due to the substrate. (c) The in-situ synchrotron radiation diffraction from the growth of RuO2 nanowires as the temperature increases to 150 ~ 600 °C. Each vertical line is one XRD scan, with the intensity represented by the color. The first scan is at the left, and time progresses right. (d) The change in the intensity of (101) and (110) plane with time and inset image is full time.
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f2: (a) SEM images and (b) the corresponding XRD patterns (● : (110), ○ : (101), ■ : (200), and □ : (211)) of RuO2 nanowires as a function of temperature (scale bar, 100 nm). The peak at 33.2 ° is due to the substrate. (c) The in-situ synchrotron radiation diffraction from the growth of RuO2 nanowires as the temperature increases to 150 ~ 600 °C. Each vertical line is one XRD scan, with the intensity represented by the color. The first scan is at the left, and time progresses right. (d) The change in the intensity of (101) and (110) plane with time and inset image is full time.

Mentions: Figure 2a shows SEM images of the as-grown RuO2 nanowires on a Si substrate synthesized by heating the RuO2 precursors in air atmosphere in the range of 150 ~ 250 °C during 4 hrs. At low temperature less than 150 °C, only nanoparticles were observed and there were no nanowires on the substrates. In ex-situ x-ray diffraction (XRD), there are no peaks in the spectra, meaning that the nanoparticles are still amorphous. As the temperature increases to 180 °C, three peaks corresponding to the (110), (101), and (211) planes were clearly observed, confirming that the amorphous nanoparticles start to be crystallized at the temperature. In the SEM image, many straight nanowires with apparent tapering at the end and without any cluster at the tip were also seen. Further increase in the temperature enhances the growth of the nanowires, increasing the intensity of the three peaks, and produces additional peak corresponding to the (200) plane. At 250 °C, the length and diameter of the nanowires are in the range of 150 nm and 18 nm, respectively. The length and diameter of the nanowires increase as the temperature increases, while the aspect ratio decreases with the temperature (Supplementary Fig. S1).


Structural Evolution of Chemically-Driven RuO2 Nanowires and 3-Dimensional Design for Photo-Catalytic Applications.

Park J, Lee JW, Ye BU, Chun SH, Joo SH, Park H, Lee H, Jeong HY, Kim MH, Baik JM - Sci Rep (2015)

(a) SEM images and (b) the corresponding XRD patterns (● : (110), ○ : (101), ■ : (200), and □ : (211)) of RuO2 nanowires as a function of temperature (scale bar, 100 nm). The peak at 33.2 ° is due to the substrate. (c) The in-situ synchrotron radiation diffraction from the growth of RuO2 nanowires as the temperature increases to 150 ~ 600 °C. Each vertical line is one XRD scan, with the intensity represented by the color. The first scan is at the left, and time progresses right. (d) The change in the intensity of (101) and (110) plane with time and inset image is full time.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4493639&req=5

f2: (a) SEM images and (b) the corresponding XRD patterns (● : (110), ○ : (101), ■ : (200), and □ : (211)) of RuO2 nanowires as a function of temperature (scale bar, 100 nm). The peak at 33.2 ° is due to the substrate. (c) The in-situ synchrotron radiation diffraction from the growth of RuO2 nanowires as the temperature increases to 150 ~ 600 °C. Each vertical line is one XRD scan, with the intensity represented by the color. The first scan is at the left, and time progresses right. (d) The change in the intensity of (101) and (110) plane with time and inset image is full time.
Mentions: Figure 2a shows SEM images of the as-grown RuO2 nanowires on a Si substrate synthesized by heating the RuO2 precursors in air atmosphere in the range of 150 ~ 250 °C during 4 hrs. At low temperature less than 150 °C, only nanoparticles were observed and there were no nanowires on the substrates. In ex-situ x-ray diffraction (XRD), there are no peaks in the spectra, meaning that the nanoparticles are still amorphous. As the temperature increases to 180 °C, three peaks corresponding to the (110), (101), and (211) planes were clearly observed, confirming that the amorphous nanoparticles start to be crystallized at the temperature. In the SEM image, many straight nanowires with apparent tapering at the end and without any cluster at the tip were also seen. Further increase in the temperature enhances the growth of the nanowires, increasing the intensity of the three peaks, and produces additional peak corresponding to the (200) plane. At 250 °C, the length and diameter of the nanowires are in the range of 150 nm and 18 nm, respectively. The length and diameter of the nanowires increase as the temperature increases, while the aspect ratio decreases with the temperature (Supplementary Fig. S1).

Bottom Line: Growth then proceeds by Ru diffusion to the nanoparticles, followed by the diffusion to the growing surface of the nanowire in oxygen ambient, supported by the nucleation theory.The RuO2 branched Au-TiO2 nanowire arrays shows a remarkable enhancement in the photocurrent density by approximately 60% and 200%, in the UV-visible and Visible region, respectively, compared with pristine TiO2 nanowires.Furthermore, there is no significant decrease in the device's photoconductance with UV-visible illumination during 1 day, making it possible to produce oxygen gas without the loss of the photoactvity.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, KIST-UNIST-Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea.

ABSTRACT
Growth mechanism of chemically-driven RuO2 nanowires is explored and used to fabricate three-dimensional RuO2 branched Au-TiO2 nanowire electrodes for the photostable solar water oxidation. For the real time structural evolution during the nanowire growth, the amorphous RuO2 precursors (Ru(OH)3 · H2O) are heated at 180 (°)C, producing the RuO2 nanoparticles with the tetragonal crystallographic structure and Ru enriched amorphous phases, observed through the in-situ synchrotron x-ray diffraction and the high-resolution transmission electron microscope images. Growth then proceeds by Ru diffusion to the nanoparticles, followed by the diffusion to the growing surface of the nanowire in oxygen ambient, supported by the nucleation theory. The RuO2 branched Au-TiO2 nanowire arrays shows a remarkable enhancement in the photocurrent density by approximately 60% and 200%, in the UV-visible and Visible region, respectively, compared with pristine TiO2 nanowires. Furthermore, there is no significant decrease in the device's photoconductance with UV-visible illumination during 1 day, making it possible to produce oxygen gas without the loss of the photoactvity.

No MeSH data available.


Related in: MedlinePlus