Photocatalytic activity evaluated through the water
splitting reaction using Ta2O5 nanotubes sensitized
with CdSe quantum dots
C. F. Melo1,2, F. Tavares1,2, I. R. S. Arruda1, N. Amorim1, P. R. S. Toledo1,2, G.
Machado1
1
Centro de Tecnologias Estratégicas do Nordeste, PE, Brazil
Universidade Federal de Pernambuco, Departamento de Engenharia Química, PE,
Brazil
As an alternative to obtainment renewable fuels, the hydrogen production by
photocatalysis has attracted great scientific and technological interests. After the work
of Honda and Fujishima in 1972[1], the hydrogen production reactions has emerged as a
viable option for cleaner fuels productions due to smaller cost and to the absence of
carbon compounds derived. Recently studies show the tantalum oxide (Ta2O5),
especially in its nanostructured form, as a promisor material for the hydrogen
photogeneration [2]. In this work, the Ta2O5 was used in the form of nanotubes (NTs),
synthesized by an anodization with sulfuric acid (H2SO4) using tantalum and copper
sheets as electrodes for 10 minutes in thermostatic bath, and submitted for an annealing
at 800ºC for 1 hour. The CdSe colloidal solution was prepared using distinct steps. The
first step consisted of reducing selenium to selenite through high-frequency ultrasonic
radiation for 5 min. In the second step the L-cysteine (1.2 mmol) was add the mixture
CdCl2 (0.4mmol) dissolved in 200mL water, after the pH was adjusted to 9.0. Finally
the selenite solution was add in the mixture L-cysteine/CdCl2. After manual stirring, a
clear, yellow suspension of CdSe QDs was obtained.
By means of the Transmission Electron Microscopy (TEM) (Figure 1a) it was
studied the Ta2O5 NTs and CdSe quantum dots morphology and EDS analysis (Figure
1c). The nanotubes were impregnates with CdSe quantum dots the catalytic activity was
evaluated through the water splitting reaction in a quartz reactor, using a 150W Xe/Hg
lamp (1 sun). The hydrogen production was observed by gas chromatography through
the period of 3 hours (Figure 1d).
2
Acknowledgments:
The authors are grateful for financial support from the following Brazilian agencies:
CAPES , CNPq, FACEPE and CETENE for technical support.
References:
[1] A. Fujishima, K. Honda, Nature 238 (1972), 37-38
F. C.; Zapata, M. J. M.; Dupont, J.; Feil, A. F.; Teixeira, S. R. Ta2O5 Nanotubes
Obtained by Anodization: Effect of Thermal Treatment on the Photocatalytic Activity
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Figure 1: 1a) TEM image of Ta2O5 NT + CdSe; 1b) Highlight Ta2O5 NT + CdSe; 1c)
EDS Analysis Ta2O5 NT + CdSe; 1d) Results of hydrogen production by water splitting
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