Woo Hyoun Woo, Kwon Yong Jung, Cho Hong Yeon, Na Han Gil
J Nanosci Nanotechnol. 2014 Nov;14(11):8242-7.
We fabricated SnO2/cobalt (Co) core-shell nanowires by means of a two-step process, for their application as chemical sensors. For Co-functionalization, we synthesized SnO2-Co core-shell nanowires by the sputtering deposition of Co layers on the surface of networked SnO2 nanowires, subsequently transforming the continuous Co-shell layers into crystalline islands by thermal heating. While scanning electron microscopy (SEM) images of annealed core-shell nanowires exhibited a rough surface, transmission electron microscopy (TEM) images revealed that the roughness is related to the agglomeration of the sputtered Co layer. The X-ray diffraction (XRD) pattern and lattice-resolved TEM images coincidentally indicated that the agglomerated particles are comprised of a hexagonal Co phase. The NO2 sensing test revealed that the sensor response was enhanced by decoration with Co nanoparticles. In addition, both response and recovery times tended to decrease as a result of the Co-functionalization. This indicates that the Co-functionalized SnO2 nanowire sensors can be used to sense gases at very low concentrations. We discussed possible mechanisms for enhancing sensor properties by Co-functionalization. The NO2 gas sensing test demonstrated the ability of the Co-functionalization to provide higher sensitivity, shorter response time, and shorter recovery time than would bare SnO2 nanowires.
我们通过两步法制备了用于化学传感器应用的二氧化锡/钴（Co）核壳纳米线。为了进行钴功能化，我们通过在网络化二氧化锡纳米线表面溅射沉积钴层来合成二氧化锡-钴核壳纳米线，随后通过热加热将连续的钴壳层转变为结晶岛。虽然退火核壳纳米线的扫描电子显微镜（SEM）图像显示表面粗糙，但透射电子显微镜（TEM）图像表明粗糙度与溅射钴层的团聚有关。X射线衍射（XRD）图谱和晶格分辨TEM图像一致表明团聚颗粒由六方钴相组成。二氧化氮传感测试表明，用钴纳米颗粒修饰可增强传感器响应。此外，由于钴功能化，响应时间和恢复时间都趋于缩短。这表明钴功能化的二氧化锡纳米线传感器可用于检测极低浓度的气体。我们讨论了通过钴功能化增强传感器性能的可能机制。二氧化氮气体传感测试表明，与裸露的二氧化锡纳米线相比，钴功能化能够提供更高的灵敏度、更短的响应时间和更短的恢复时间。
