Poster MRS Hydrogen Production

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DESIGN OF TITANIA NANOTUBE ARRAYS FOR THE PHOTOELECTROCATALYTIC WATER SPLITTING REACTION P. J. Arias-Monje 1* , F. J. Q. Cortés 1 , H. Zea 1 , C. C. Luhrs 2 This work was performed under the auspices of the National University of Colombia and Colciencias, grants number 19163 of the program “Convocatoria del Programa Nacional de Proyectos para el Fortalecimiento de la Investigación, la Creación y la Innovación en Posgrados de la Universidad Nacional de Colombia 2013-2015” and 21551 of the program “Jóvenes Investigadores de Colciencias - 2013”, respectively. Many thanks as well to E.S.K. Menon and J. Phillips. Acknowledgements GOAL 2% 4% 6% 8% 10% 0 50 100 150 Photocurrent efficiency (%) Aspect ratio (length/diameter) 150 nm 240 nm 320 nm 2% 6% 9% 13% 16% 0 9 18 27 Photocurrent efficiency (%) Number of rings Diameter: 240 nm Length: 9 μm 100 150 200 250 300 350 400 3 6 9 Diameter (nm) Water content (%) 0 5 10 15 20 25 1 10 100 1000 Tube length (μm) Anodizing time (min) Log scale 3.8% 6.9% 10.0% Tube diameter and length vary linearly with water content and anodizing time, respectively. 1 National University of Colombia, Bogotá, Colombia 2 Naval Postgraduate School, Monterey, CA, United States *[email protected] Institutions Water: 6.9% 10% 1 st step 2 nd step Surface changes Only diameter changes Two-step anodizing increases uniformity at the top of the arrays, regardless of the water content. To describe the photoelectrocatalytic (PEC) response for hydrogen generation of the TiO 2 nanomaterial by tuning its morphology: diameter, length and roughness. Influence of diameter and tube length has not been completely understood due to the difficulty of varying them as independent variables and the fact that top morphology variations can obscure those effects. Dependence of morphology on synthesis conditions (above) Effect of morphology on the PEC response (1.6 mW/cm 2 UVA light, Ni wire cathode, -0.5V bias vs. Ag/AgCl reference electrode) (below) Various roughness were obtained varying the number of rings on the outer walls of the nanotubes by alternating voltage anodizing BACKGROUND The nanotubes were produced at 100 V in ethylene glycol and ammonium fluoride solution Photocurrent efficiency increases with the number of rings, due to an increase in the effective surface area without compromising aspect ratio. No rings 9 rings Photocurrent efficiency depends on the aspect ratio of the arrays (optimal value around 20) PEC response of tubes of 240 nm of diameter, 9 μm of length and different number of rings CONCLUSIONS

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poster presented during MRS 2015. DESIGN OF TITANIA NANOTUBE ARRAYS FOR THE PHOTOELECTROCATALYTIC WATER SPLITTING REACTION

Transcript of Poster MRS Hydrogen Production

  • DESIGN OF TITANIA NANOTUBE ARRAYS FOR THE

    PHOTOELECTROCATALYTIC WATER SPLITTING REACTION

    P. J. Arias-Monje1*, F. J. Q. Corts1, H. Zea1, C. C. Luhrs2

    This work was performed under the auspices of the National University of Colombia and Colciencias, grants number 19163 of the program Convocatoria del Programa Nacional de Proyectos para el Fortalecimiento de la Investigacin, la Creacin y la Innovacin en Posgrados de la Universidad Nacional de Colombia

    2013-2015 and 21551 of the program Jvenes Investigadores de Colciencias - 2013, respectively. Many thanks as well to E.S.K. Menon and J. Phillips.

    Acknowledgements

    GOAL

    2%

    4%

    6%

    8%

    10%

    0 50 100 150

    Ph

    oto

    curr

    ent

    effi

    cien

    cy(%

    )

    Aspect ratio (length/diameter)

    150 nm 240 nm 320 nm2%

    6%

    9%

    13%

    16%

    0 9 18 27

    Ph

    oto

    curr

    ent

    effi

    cien

    cy (

    %)

    Number of rings

    Diameter: 240 nmLength: 9 m

    100

    150

    200

    250

    300

    350

    400

    3 6 9

    Dia

    met

    er (

    nm

    )

    Water content (%)

    0

    5

    10

    15

    20

    25

    1 10 100 1000

    Tub

    e le

    ngt

    h (

    m

    )

    Anodizing time (min) Log scale

    3.8%

    6.9%

    10.0%

    Tube diameter and length vary linearly withwater content and anodizing time, respectively.

    1National University of Colombia, Bogot, Colombia2Naval Postgraduate School, Monterey, CA, United States

    *[email protected]

    Institutions

    Water: 6.9% 10%

    1st

    step

    2nd

    step

    Surface changes

    Only diameter changes

    Two-step anodizing increases uniformity atthe top of the arrays, regardless of the

    water content.

    To describe the photoelectrocatalytic (PEC)

    response for hydrogen generation of the TiO2nanomaterial by tuning its morphology: diameter,

    length and roughness.

    Influence of diameter and tube length has not been

    completely understood due to the difficulty of varying

    them as independent variables and the fact that top

    morphology variations can obscure those effects.

    Dependence of morphology on synthesis conditions

    (above)

    Effect of morphology on the PEC response (1.6 mW/cm2

    UVA light, Ni wire cathode, -0.5V bias vs. Ag/AgCl

    reference electrode) (below)

    Various roughness were obtained varying the

    number of rings on the outer walls of the nanotubes

    by alternating voltage anodizing

    BA

    CKG

    RO

    UN

    D

    The nanotubes were produced at 100 V in ethylene glycol

    and ammonium fluoride solution

    Photocurrent efficiency increases withthe number of rings, due to an increase

    in the effective surface area without

    compromising aspect ratio.

    No rings 9 rings

    Photocurrent efficiency depends on the aspectratio of the arrays (optimal value around 20)

    PEC response of tubes of 240 nm of diameter, 9 m of

    length and different number of rings

    CO

    NC

    LUSI

    ON

    S