Nanoporous tin oxides synthesized via electrochemical anodization in oxalic acid and their photoelectrochemical activity
| Autor: | Leszek Zaraska, Aleksandra Krzysik, Tomasz Łojewski, Karolina Syrek, Grzegorz D. Sulka, Marian Jaskuła, Katarzyna E. Hnida, M. Bobruk |
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| Rok vydání: | 2016 |
| Předmět: |
Photocurrent
Materials science Annealing (metallurgy) Anodizing Band gap Nanoporous General Chemical Engineering Inorganic chemistry Oxide chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Tin oxide 01 natural sciences 0104 chemical sciences chemistry.chemical_compound chemistry Chemical engineering Electrochemistry 0210 nano-technology Tin |
| Zdroj: | Electrochimica Acta. 205:273-280 |
| ISSN: | 0013-4686 |
| DOI: | 10.1016/j.electacta.2016.02.023 |
| Popis: | Nanoporous tin oxide layers were obtained by one-step potentiostatic anodization carried out in 0.3 M H 2 C 2 O 4 followed by thermal annealing at temperatures in the range of 200–700 °C. The morphology and crystallinity of as obtained oxide layers were characterized by SEM, and XRD, respectively. It was confirmed, that after 10 min of anodic oxidation at the potential of 8 V, anodic tin oxide consists of a dense array of randomly distributed nanopores with an average diameter of about 50–60 nm. Moreover, such kind of porous structures is maintained during annealing at temperatures up to 500 °C. On the contrary, for higher annealing temperatures a transformation of nanoporous layers into particle-like structures was evident. A gradual increase of the crystallite size with increasing annealing temperature was also confirmed. Finally, photoelectrochemical properties of anodic tin oxide layers, annealed at temperatures in the range of 400–700 °C, were extensively investigated. The best photoelectrochemical performance with the maximum photocurrent densities of above 25 μA cm −2 and conversion efficiency of about 30% was observed for sample annealed at 500 °C. Higher annealing temperatures result in a gradual decrease in photocurrent densities that can be attributed to the change in the sample morphology and decrease in electrochemical reaction sites. Optical band gap energies were determined on the basis of UV–vis reflectance spectra and photocurrent measurements, and a gradual increase in the band gap energy with increasing annealing temperature was confirmed. |
| Databáze: | OpenAIRE |
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