Fabrication of metal-shelled coaxial nanowires and annealing-induced formation of metal nanoparticles for catalytic applications: Growth and characteristics of SnO2-branched nanostructures

We have fabricated SnO2 branches on SiOx stem nanowires, via a novel multi-step process. With the SnO2 branches having diameters in the range 20–80 nm, X-ray diffraction, transmission electron microscopy and selected area diffraction pattern coincidentally revealed that the branches were crystalline rutile SnO2 structures. We suggested that a Ag-catalyzed base-growth vapor–liquid–solid growth mechanism was responsible for the growth of SnO2 branches. Photoluminescence analysis indicated that the Ag-coated SiOx nanowires exhibited emission bands centered at 2.6 eV and 3.1 eV, presumably from the SiOx core nanowires. Subsequent annealing induced 2.4-eV band, whereas the growth of SnO2 branches induced 2.1-eV band. For the branched product, we have investigated the O2 and NO2 sensing properties. A linear relationship between sensitivity and the O2 gas concentration was observed, which demonstrates its potential application to chemical sensors.

Graphical abstractWe have fabricated SnO2 branches on SiOx stem nanowires, via a novel multi-step process. We suggested that a Ag-catalyzed base-growth vapor–liquid–solid growth mechanism was responsible for the growth of SnO2 branches. For the branched product, we have investigated the O2 and NO2 sensing properties. A linear relationship between sensitivity and the O2 gas concentration was observed, which demonstrates its potential application to chemical sensors.Figure optionsDownload full-size imageDownload as PowerPoint slide