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Improvement of Solar Energy Conversion with Nb-Incorporated TiO2 Hierarchical Microspheres

Authors

  • Son Hoang,

    1. Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)
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  • Thong Q. Ngo,

    1. Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)
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  • Sean P. Berglund,

    1. Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)
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  • Raymond R. Fullon,

    1. Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)
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  • Prof. John G. Ekerdt,

    1. Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)
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  • Prof. C. Buddie Mullins

    Corresponding author
    1. Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)
    • Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science Department, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712-0231 (USA)

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Abstract

Niobium-modified TiO2 hierarchical spherical micrometer-size particles, which consist of many nanowires, are synthesized by solvothermal synthesis and studied as photoelectrodes for water photo-oxidation and dye-sensitized solar cell (DSSC) applications. Incorporation of Nb leads to a rutile-to-anatase TiO2 phase transition in the TiO2 hierarchical spheres (HSs), with the anatase percentage increasing from 0 % for the pristine TiO2 HSs to 47.6 % for the 1.82 at. % Nb-incorporated TiO2 sample. Incorporation of Nb leads to significant improvements in water photo-oxidation with the photocurrents reaching 70.5 μA cm−2 at 1.23 V versus the reversible hydrogen electrode, compared with 28.3 μA cm−2 for the pristine TiO2 sample. The photoconversion efficiency of Nb:TiO2 HS-based DSSCs reaches 6.09±0.15 % at 0.25 at. % Nb, significantly higher than that for the pristine TiO2 HS cells (3.99±0.02 %). In addition, the incident-photon-to-current efficiency spectra for DSSCs show that employing TiO2 and Nb:TiO2 HSs provides better light harvesting, especially of long-wavelength photons, than anatase TiO2 nanoparticle-based DSSCs.

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