1차원 산화물 나노와이어의 합성 및 특성연구

Abstract

(1) 온도 조절을 통한 Bi4Ge3O12 나노와이어의 합성 및 특성.

Bi와 Ge 파우더를 이용하여 Heating 온도를 변화시키며 Bi4Ge3O12 나노와이어를 합성하였다. 800 ℃ 에서의 성장은 VS 메커니즘을 통해 진행하는 반면, 600 ℃ 에서의 성장은 주로 VLS 메커니즘에 지배적이었다. 600 ℃ 로 성장한 나노와이어는 Bi, Ge, O, Au로 구성된 비정질상이었으나 tip에 위치하는 것으로 보았을 때 Bi, Au가 촉매로 작용된 것으로 확인된다. 800 ℃ 로 성장된 나노와이어는 tip과 stem에 입방정의 Bi4(GeO4), Bi2O3, GeO2 3가지 종류의 물질로 확인되었다. 이는 800 ℃ 로 성장된 나노와이어의 PL특성에서 다양한 Peak로 발현되는 것으로 확인되었다. Bi4(GeO4) 나노와이어로 자성을 측정하였는데 강자성 거동을 나타내는 hysteresis loop로 보여진다.

(2) p-type CuO 나노파티클을 이용한 SnO2 브랜치구조의 가스센서 특성 향상.

Cu로 코팅된 SnO2 나노와이어의 어닐링을 통하여 SnO2 나노와이어를 Cu-촉매 기반의 SnO2 브랜치구조를 합성하였다. 어닐링온도(500 ℃ -700 ℃ )에 따른 모폴로지의 변화를 확인하였다. Tip의 확인하였을 때 500 ℃ 와 700 ℃ 온도로 성장시킨 브랜치구조는 VLS 메커니즘이 지배적으로 작용하는 것으로 보여진다. 700 ℃ 에서의 tip 나노파티클은 CuO상이다. SnO2 브랜치 나노와이어에 CuO 기능화를 적용하여 H2S 가스센서에 적용하였다. CuO 기능화로 H2S의 Response의 증가를 확인하였다. 대조적으로 NO2에 대한 Response는 감소하였다. CuO 기능화된 SnO2 브랜치 나노와이어는 H2S 가스에 대한 고선택도 센서특성에 대해 기술하였다. |(1) Temperature-controlled synthesis and characterization of Bi4Ge3O12 nanowires

Varying the heating temperature of a mixture of Bi and Ge powders, we have successfully prepared Bi4Ge3O12 nanowires. The growth at 600 ℃ was mainly controlled via a vapor-liquid-solid process, whereas the growth at 800 ℃ was dominated by a vapor-solid mechanism. Although 600 ℃ -grown nanowires were amorphous, being comprised of Bi, Ge, O, and Au elements, the Bi and Au elements prevalently resided in the tip, playing a catalytic role in the nanowire growth. For 800 ℃ -grown nanowires, both the stem and tip were mainly comprised of cubic Bi4(GeO4)3 phase with additional Bi2O3 and GeO2 phases. It was observed that the photoluminescence spectrum of 800 ℃ -grown nanowires is comprised of several peaks with respect to Bi2O3,GeO2 ,and Bi4Ge3O12 phases. The magnetic measurements showed that the Bi4Ge3O12 nanowires exhibited a hysteresis loop, indicating ferromagnetic behavior.

(2) A novel growth of CuO-functionalized, branched SnO2 nanowires and their application to H2S sensors

A novel growth method for CuO-functionalized, branched tin oxide (SnO2) nanowires has been developed on the basis of Cu-triggered tip-growth vapor-liquid-solid process during annealing the Cu-coated SnO2 nanowires. The variation in annealing temperature changed the morphology, in which higher temperatures (≥500 ℃ ) is favorable for the formation of branches. From the observation of tip nanoparticles, we revealed that the growth of branches at 500 and 700 ℃ were dominated by base-growth and tip-growth vapor-liquid-solid process, respectively. The tip nanoparticles at 700 ℃. we remainly comprised of a CuO phase. We have demonstrated the potential applicability of the CuO-functionalized, branched SnO2 nanowires to H2S sensors. The CuO-functionalization greatly enhanced the response to H2S. In sharp contrast, it degraded the response to NO2, suggesting their selective sensing performance to H2S.; (1) Temperature-controlled synthesis and characterization of Bi4Ge3O12 nanowires

Varying the heating temperature of a mixture of Bi and Ge powders, we have successfully prepared Bi4Ge3O12 nanowires. The growth at 600 ℃ was mainly controlled via a vapor-liquid-solid process, whereas the growth at 800 ℃ was dominated by a vapor-solid mechanism. Although 600 ℃ -grown nanowires were amorphous, being comprised of Bi, Ge, O, and Au elements, the Bi and Au elements prevalently resided in the tip, playing a catalytic role in the nanowire growth. For 800 ℃ -grown nanowires, both the stem and tip were mainly comprised of cubic Bi4(GeO4)3 phase with additional Bi2O3 and GeO2 phases. It was observed that the photoluminescence spectrum of 800 ℃ -grown nanowires is comprised of several peaks with respect to Bi2O3,GeO2 ,and Bi4Ge3O12 phases. The magnetic measurements showed that the Bi4Ge3O12 nanowires exhibited a hysteresis loop, indicating ferromagnetic behavior.

(2) A novel growth of CuO-functionalized, branched SnO2 nanowires and their application to H2S sensors

A novel growth method for CuO-functionalized, branched tin oxide (SnO2) nanowires has been developed on the basis of Cu-triggered tip-growth vapor-liquid-solid process during annealing the Cu-coated SnO2 nanowires. The variation in annealing temperature changed the morphology, in which higher temperatures (≥500 ℃ ) is favorable for the formation of branches. From the observation of tip nanoparticles, we revealed that the growth of branches at 500 and 700 ℃ were dominated by base-growth and tip-growth vapor-liquid-solid process, respectively. The tip nanoparticles at 700 ℃. we remainly comprised of a CuO phase. We have demonstrated the potential applicability of the CuO-functionalized, branched SnO2 nanowires to H2S sensors. The CuO-functionalization greatly enhanced the response to H2S. In sharp contrast, it degraded the response to NO2, suggesting their selective sensing performance to H2S.