Facile Synthesis Procedure of TiO2 Core(Rutile)-Shell(Anatase) Nanorods as a Highly Efficient Solar Water-Splitter
| Autor: | HOGIARTHA SUTIONO |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 In this study, the crystal growth behavior of TiO2 nanorods (NRs) array, which was directly grown on the FTO substrate, could be controlled through a simple procedure. It was found that the position of FTO substrate inside the Teflon-liner during hydrothermal synthesis was strikingly important to control the preferred crystal growth direction. By simply changing the position of FTO substrate, TiO2 NRs array with unusual crystallographic properties could be obtained. Interestingly, it could produce a remarkable saturation photocurrent of 2.32 mA cm-2 at 1.23 VRHE which outclassed any published reports for pristine TiO2 photoanode water-splitter. Initially, the finding of unusual crystallographic properties ((110) and (101) facets) was believed severely enhanced the photoelectrochemical (PEC) water-splitting performance. But, after the anatase phase was found in the NRs system, the exact role of (110) and (101) facets towards this superior PEC water-splitting performance became obscured. The existence of anatase phase, which was revealed by Raman spectroscopy technique, was considered to be the main factor in improving charge separation and PEC water-splitting performance simultaneously. The strategy of adding saturated aqueous solution of a particular salt additive into the crystal growth solution not only could modulate the interaction between NRs, but also could control the portion of anatase phase in the NRs system. It was understandable that the wider distance between NRs could enlarge the accessible surface area of the NRs which could facilitate a better charge transfer in the electrode/electrolyte interface. Regarding the arrangement between rutile and anatase phases in the NRs, it was predicted that the anatase phase was naturally formed on the surface of NRs (anatase phase acted as the shell part). This prediction got confirmed by the Transmission Electron Microscopy (TEM) and Tip Enhanced Raman Spectroscopy (TERS) results which were taken from the edge of the nanorod. In addition, annealing temperature variation was selected to investigate the phase transformation and its effect on PEC water-splitting performance. Lastly, it is noteworthy that the existence of anatase phase was not the only factor that could enhance the PEC water-splitting performance. The unusual crystallographic properties of the rutile core part as the result of FTO substrate position modification during hydrothermal synthesis, was believed also responsible in this superior performance. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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