| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Nanomaterials | Wednesday Sessions |
| Session NM-WeP |
| Session: | Nanomaterials Poster Session |
| Presenter: | Taiki Ihara, Tokyo Institute of Technology, Japan |
| Authors: | T. Ihara, Tokyo Institute of Technology, Japan K. Katsumata, Tokyo Institute of Technology, Japan T. Watanabe, Meiji University, Japan K. Okada, Tokyo Institute of Technology, Japan N. Matsushita, Tokyo Institute of Technology, Japan |
| Correspondent: | Click to Email |
Recent research has shown that N-doping into TiO2, Ta2O5, or LaTaO4 is effective for narrowing the band-gap and attaining the visible-light photocatalysis. N-doped metal oxide powder is commonly synthesized by elevating metal oxide specimens temperature over 500oC with flowing ammonia gas or nitrogen. In this study, we succeeded in synthesizing N-containing ZnO rods by hydrothermal process using ammine-hydroxo zinc complex solution at 100oC.
10 ml of 2.5 M NaOH (aq) was added in drops to 15 ml of 0.5 M Zn (NO3)2･6H2O aqueous solution over stirring vigorously. The resulting hydroxide slurry was centrifuged and the supernatant was removed. The hydrated precipitate was dissolved in 50 ml of 6.6 M NH3 (aq) to form a stock solution. 30 ml of the solution was transferred into a 35 ml Teflon-lined stainless steel autoclave, followed by heating in an oven at 100oC for 6-24 h. After the reaction, the precipitates were separated by centrifugation, and then washed with water.
The diffraction peaks in XRD patterns for synthesized sample was good agreement with those of the hexagonal wurtzite structure of ZnO (JCPDS card 36-1451). The morphology of the ZnO particles were hexagonal rods and the size was about 20 μm in long axis and about 1 μm in diameter. UV-vis spectra for the sample prepared for different reaction time revealed that the absorption band was shifted to visible region as increasing the reaction time. In the raman spectra, typical Ramanactive modes for ZnO (E2, A1(TO), A1(LO), E1(TO), and E1(LO)) were clearly observed for all samples. In addition to the above, new peak was observed at 582 cm-1 on N-containing ZnO rod which is attributed to the E2(Zn-N) mode. N concentration calculated from XPS data was increased as increasing the reaction time. XPS spectrum of N 1s for the sample prepared at 100oC for 6 h showed the asymmetric broad peak indicating that more than one chemical states of N were present. The binding energy at ∼399.0 eV was attributed to the surface species of NH3 or amines. The another peak at ∼397.0 eV was ascribed to N atom in Zn-N bond indicating that N was incorporated in ZnO rods.