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Influence of anodization time on the surface modifications on α-Fe2O3 photoanode upon anodization

Published online by Cambridge University Press:  19 February 2016

Kelebogile Maabong*
Affiliation:
Department of Physics, University of Pretoria, Pretoria 0028, South Africa; Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland; and Department of Physics, University of Botswana, UB 0022 Gaborone, Botswana
Yelin Hu
Affiliation:
Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland; and Laboratory for Photonics and Interfaces, EPFL, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland
Artur Braun
Affiliation:
Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
Augusto G.J. Machatine
Affiliation:
Department of Physics, University of Pretoria, Pretoria 0028, South Africa
Mmantsae Diale*
Affiliation:
Department of Physics, University of Pretoria, Pretoria 0028, South Africa; and Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
*
a)Address all correspondence to these authors. e-mail: kelemaabong@gmail.com
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Abstract

In searching for a suitable semiconductor material for hydrogen production via photoelectrochemical water splitting, α-Fe2O3 received significant attention as a promising photoanode due to its band gap (∼2.1 eV), good stability, low cost, and natural occurrence. α-Fe2O3 thin films were prepared by economic and facile dip coating method and subsequently subjected to an anodic potential of 700 mV versus Ag/AgCl in 1M KOH for different anodization times (1, 10, and 900 min) under illumination. X-ray diffractometry revealed increase in crystallites size from ∼31 nm for nanoparticles in pristine state to ∼38 and 44 nm after anodization for 1 and 900 min, respectively. A clear positive correlation between anodization time and grain (particle) size was observed from field emission gun scanning electron microscopy and atomic force microscopy (AFM); longer exposure time to anodizing conditions resulted in larger grains. Grain size increased from ∼57.9 nm in pristine state to ∼153.5 nm after anodization for 900 min. A significant smoothening of the surface with increase in anodization time was evident from AFM analysis.

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Articles
Copyright
Copyright © Materials Research Society 2016 

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References

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