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Anatase TiO2 Nanoparticles with Exposed {001} Facets for Efficient Dye-Sensitized Solar Cells.

Chu L, Qin Z, Yang J, Li X - Sci Rep (2015)

Bottom Line: At the first-step hydrothermal reaction, H-titanate nanowires were obtained in NaOH solution with Ti powder, and at second-step hydrothermal reaction, anatase TiO2 nanoparticles with exposed {001} facets were formed in NH4F solution.If the second-step hydrothermal reaction was carried out in pure water, the H-titanate nanowires were decomposed into random shape anatase-TiO2 nanostructures, as well as few impurity of H2Ti8O17 phase and rutile TiO2 phase.Then, the as-prepared TiO2 nanostructures synthesized in NH4F solution and pure water were applied to the photoanodes of dye-sensitized solar cells (DSSCs), which exhibited power conversion efficiency (PCE) of 7.06% (VOC of 0.756 V, JSC of 14.80 mA/cm(2), FF of 0.631) and 3.47% (VOC of 0.764 V, JSC of 6.86 mA/cm(2), FF of 0.662), respectively.

View Article: PubMed Central - PubMed

Affiliation: School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046, P. R. China.

ABSTRACT
Anatase TiO2 nanoparticles with exposed {001} facets were synthesized from Ti powder via a sequential hydrothermal reaction process. At the first-step hydrothermal reaction, H-titanate nanowires were obtained in NaOH solution with Ti powder, and at second-step hydrothermal reaction, anatase TiO2 nanoparticles with exposed {001} facets were formed in NH4F solution. If the second-step hydrothermal reaction was carried out in pure water, the H-titanate nanowires were decomposed into random shape anatase-TiO2 nanostructures, as well as few impurity of H2Ti8O17 phase and rutile TiO2 phase. Then, the as-prepared TiO2 nanostructures synthesized in NH4F solution and pure water were applied to the photoanodes of dye-sensitized solar cells (DSSCs), which exhibited power conversion efficiency (PCE) of 7.06% (VOC of 0.756 V, JSC of 14.80 mA/cm(2), FF of 0.631) and 3.47% (VOC of 0.764 V, JSC of 6.86 mA/cm(2), FF of 0.662), respectively. The outstanding performance of DSSCs based on anatase TiO2 nanoparticles with exposed {001} facets was attributed to the high activity and large special surface area for excellent capacity of dye adsorption.

No MeSH data available.


N2 adsorption isotherms and absorption spectra.(a) N2 adsorption isotherms of random shape TiO2 nanostructures (noted “Without F−”) and truncated octahedron TiO2 nanoparticles (noted “With F−”). (b) UV-Vis absorption spectrum of random shape TiO2 nanostructure films (without/with sensitizing, i/iii) and truncated octahedron TiO2 nanoparticle films (without/with sensitizing, ii/iv) on FTO substrates. The inset shows optical images of TiO2 films (without/with sensitizing) on FTO substrates.
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f6: N2 adsorption isotherms and absorption spectra.(a) N2 adsorption isotherms of random shape TiO2 nanostructures (noted “Without F−”) and truncated octahedron TiO2 nanoparticles (noted “With F−”). (b) UV-Vis absorption spectrum of random shape TiO2 nanostructure films (without/with sensitizing, i/iii) and truncated octahedron TiO2 nanoparticle films (without/with sensitizing, ii/iv) on FTO substrates. The inset shows optical images of TiO2 films (without/with sensitizing) on FTO substrates.

Mentions: It is well-known that the nanoparticle films have large special surface area to load more dye molecules1. Therefore, the special surface area was checked by Brunauer-Emmett-Teller (BET) data as shown in Fig. 6(a). The BET surface area was measured as 40.9 and 44.6 m2/g for random shape TiO2 nanostructures and TiO2 nanoparticles, respectively. The special surface area of TiO2 nanoparticles was slightly bigger than that of the random shape TiO2 nanostructures. More importantly, exposing highly reactive {001} facets of TiO2 can enhance dye adsorption17. Thus, we investigated the amount of absorbed dye molecules to elucidate the factor of ηlh. The optical image of TiO2 and sensitized-TiO2 films on FTO substrates was shown as the inset in Fig. 6(b). The color of random shape TiO2 nanostructure films (i) was lutescent, while the color of TiO2 nanoparticle films (ii) was pure white. After being sensitized by N719 dye, the color of the sensitized-TiO2 films based on TiO2 nanoparticles (iv) was darker red than that of based on random shape TiO2 nanostructures (iii), indicating that the TiO2 nanoparticles with exposed {001} facets absorbed more dye molecules. The UV-vis absorbance measurements in Fig. 6(b) revealed the sensitized-TiO2 films based on TiO2 nanoparticles (iv) had a stronger visible absorption, because of more amount of loading dye molecules. The absorbed dye amounts were calculated from UV-vis absorbance measurements of the concentration desorbed N719 dye in NaOH solution by using Lambert-Beer’s Law3738. The absorbed dye amount of photoanodes based on TiO2 nanopartiles with exposed {001} facets was about four times than that of based on random shape TiO2 nanostructures, as listed in Table 1. The TiO2 nanoparticles with exposed {001} facets had excellent capacity for adsorption of dye molecules. As a consequence, anatase TiO2 nanoparticles with exposed {001} facets were efficient photoanodes for DSSCs.


Anatase TiO2 Nanoparticles with Exposed {001} Facets for Efficient Dye-Sensitized Solar Cells.

Chu L, Qin Z, Yang J, Li X - Sci Rep (2015)

N2 adsorption isotherms and absorption spectra.(a) N2 adsorption isotherms of random shape TiO2 nanostructures (noted “Without F−”) and truncated octahedron TiO2 nanoparticles (noted “With F−”). (b) UV-Vis absorption spectrum of random shape TiO2 nanostructure films (without/with sensitizing, i/iii) and truncated octahedron TiO2 nanoparticle films (without/with sensitizing, ii/iv) on FTO substrates. The inset shows optical images of TiO2 films (without/with sensitizing) on FTO substrates.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507182&req=5

f6: N2 adsorption isotherms and absorption spectra.(a) N2 adsorption isotherms of random shape TiO2 nanostructures (noted “Without F−”) and truncated octahedron TiO2 nanoparticles (noted “With F−”). (b) UV-Vis absorption spectrum of random shape TiO2 nanostructure films (without/with sensitizing, i/iii) and truncated octahedron TiO2 nanoparticle films (without/with sensitizing, ii/iv) on FTO substrates. The inset shows optical images of TiO2 films (without/with sensitizing) on FTO substrates.
Mentions: It is well-known that the nanoparticle films have large special surface area to load more dye molecules1. Therefore, the special surface area was checked by Brunauer-Emmett-Teller (BET) data as shown in Fig. 6(a). The BET surface area was measured as 40.9 and 44.6 m2/g for random shape TiO2 nanostructures and TiO2 nanoparticles, respectively. The special surface area of TiO2 nanoparticles was slightly bigger than that of the random shape TiO2 nanostructures. More importantly, exposing highly reactive {001} facets of TiO2 can enhance dye adsorption17. Thus, we investigated the amount of absorbed dye molecules to elucidate the factor of ηlh. The optical image of TiO2 and sensitized-TiO2 films on FTO substrates was shown as the inset in Fig. 6(b). The color of random shape TiO2 nanostructure films (i) was lutescent, while the color of TiO2 nanoparticle films (ii) was pure white. After being sensitized by N719 dye, the color of the sensitized-TiO2 films based on TiO2 nanoparticles (iv) was darker red than that of based on random shape TiO2 nanostructures (iii), indicating that the TiO2 nanoparticles with exposed {001} facets absorbed more dye molecules. The UV-vis absorbance measurements in Fig. 6(b) revealed the sensitized-TiO2 films based on TiO2 nanoparticles (iv) had a stronger visible absorption, because of more amount of loading dye molecules. The absorbed dye amounts were calculated from UV-vis absorbance measurements of the concentration desorbed N719 dye in NaOH solution by using Lambert-Beer’s Law3738. The absorbed dye amount of photoanodes based on TiO2 nanopartiles with exposed {001} facets was about four times than that of based on random shape TiO2 nanostructures, as listed in Table 1. The TiO2 nanoparticles with exposed {001} facets had excellent capacity for adsorption of dye molecules. As a consequence, anatase TiO2 nanoparticles with exposed {001} facets were efficient photoanodes for DSSCs.

Bottom Line: At the first-step hydrothermal reaction, H-titanate nanowires were obtained in NaOH solution with Ti powder, and at second-step hydrothermal reaction, anatase TiO2 nanoparticles with exposed {001} facets were formed in NH4F solution.If the second-step hydrothermal reaction was carried out in pure water, the H-titanate nanowires were decomposed into random shape anatase-TiO2 nanostructures, as well as few impurity of H2Ti8O17 phase and rutile TiO2 phase.Then, the as-prepared TiO2 nanostructures synthesized in NH4F solution and pure water were applied to the photoanodes of dye-sensitized solar cells (DSSCs), which exhibited power conversion efficiency (PCE) of 7.06% (VOC of 0.756 V, JSC of 14.80 mA/cm(2), FF of 0.631) and 3.47% (VOC of 0.764 V, JSC of 6.86 mA/cm(2), FF of 0.662), respectively.

View Article: PubMed Central - PubMed

Affiliation: School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046, P. R. China.

ABSTRACT
Anatase TiO2 nanoparticles with exposed {001} facets were synthesized from Ti powder via a sequential hydrothermal reaction process. At the first-step hydrothermal reaction, H-titanate nanowires were obtained in NaOH solution with Ti powder, and at second-step hydrothermal reaction, anatase TiO2 nanoparticles with exposed {001} facets were formed in NH4F solution. If the second-step hydrothermal reaction was carried out in pure water, the H-titanate nanowires were decomposed into random shape anatase-TiO2 nanostructures, as well as few impurity of H2Ti8O17 phase and rutile TiO2 phase. Then, the as-prepared TiO2 nanostructures synthesized in NH4F solution and pure water were applied to the photoanodes of dye-sensitized solar cells (DSSCs), which exhibited power conversion efficiency (PCE) of 7.06% (VOC of 0.756 V, JSC of 14.80 mA/cm(2), FF of 0.631) and 3.47% (VOC of 0.764 V, JSC of 6.86 mA/cm(2), FF of 0.662), respectively. The outstanding performance of DSSCs based on anatase TiO2 nanoparticles with exposed {001} facets was attributed to the high activity and large special surface area for excellent capacity of dye adsorption.

No MeSH data available.