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Visible Light Induced Photocatalytic Activity of N-doped TiO2

질소 도핑된 이산화티타늄의 가시광 광촉매 활성 연구

  • Lee, Seo Hee (Department of Environmental Engineering, Kongju National University) ;
  • Lee, Chang-Yong (Department of Environmental Engineering, Kongju National University)
  • Received : 2017.12.21
  • Accepted : 2018.02.22
  • Published : 2018.06.10

Abstract

Photocatalytic properties of nitrogen doped titanium dioxide were investigated. Photocatalytic degradation of methylene blue under UV and visible light was carried out to characterize N-doped $TiO_2$. The result of XPS indicated that nitrogen atoms substitute for oxygen sites within the crystal structure of $TiO_2$. In the UV-Vis DRS spectra, N-doped amorphous $TiO_2$ absorbed UV light with little absorption of visible light, while the absorption of visible light of amorphous/anatase $TiO_2$ remarkably increased. Methylene blue photocatalytic degradation appeared by the irradiation of UV or visible light onto the N-doped anatase phase of $TiO_2$. However, the degradation rate of visible light was lower than that of UV light. The photocatalytic degradation rate of the amorphous/anatase $TiO_2$ sample was higher than that of the anatase $TiO_2$. These results indicate that the high surface area of amorphous/anatase $TiO_2$ sample, which was about three times larger than those of the anatase $TiO_2$ sample, may be related to small particles of N-doped anatase $TiO_2$.

질소가 도핑된 이산화티타늄의 광촉매 특성을 알아보았다. 질소가 도핑된 이산화티타늄에 대하여 자외선 및 가시광선 분위기에서 메틸렌블루 광촉매 분해를 수행하였다. XPS 분석을 통해 제조한 $TiO_2$에서 질소(N)가 산소(O)와 치환되었음을 확인하였다. UV-Vis DRS 분석 결과 질소가 도핑된 무정형 $TiO_2$ 시료에서는 가시광선을 거의 흡수하지 않고 자외선을 흡수하는 반면 무정형/anatase 혼재 $TiO_2$ 시료의 경우 가시광선 흡수가 상당히 증가하였다. 질소가 도핑된 anatase $TiO_2$ 시료는 자외선 및 가시광선 조사에서 메틸렌블루 광분해 반응이 나타났다. 그러나 가시광선 조사에서 분해율은 자외선 조사의 분해율보다 낮았다. 무정형/anatase 혼재 $TiO_2$ 시료의 경우 자외선과 가시광선 조사에서 anatase $TiO_2$ 시료의 분해율보다 높았다. 이러한 결과는 anatase $TiO_2$ 시료에 비해 3배 정도 큰 무정형/anatase 혼재 $TiO_2$ 시료의 높은 표면적이 질소 도핑된 작은 anatase 입자와 관련이 있음을 보여준다.

Keywords

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