Tin–copper mixed metal oxide nanowires: Synthesis and sensor response to chemical vapors

Tin–copper mixed metal oxide nanowires were successfully prepared by thermally oxidizing electrodeposited metallic nanowires (Sn–8 at.% Cu, Sn–43 at.% Cu and Sn–86 at.% Cu). The structure and composition of these nanowires before and after thermal oxidation were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). Dielectrophoresis was utilized to align the nanowires in contact with pre-fabricated interdigitated electrodes to form a chemiresistive gas sensor circuit. The sensitivity variation of the nanowires with different compositions was tested with acetone, ethanol and ethyl acetate vapors at different concentration levels, and the temperature effect was studied at five operating temperatures, ranging from 200 °C to 440 °C. All the three mixed metal oxide nanowire sensors exhibited higher sensitivity than that of pure tin oxide nanowire sensor. The sensor performance was also investigated in terms of response/recovery time and repeatability. An interesting positive/negative response was observed by varying the element composition of the mixed oxide nanowires.

► Tin-copper mixed metal oxide nanowires for organic vapor sensing.
► High sensitivity and good response and recovery time as sensing materials.
► Sensor performance variation dependent on tin-copper ratios from low to high copper contents.
► Rough nanowire surface decorated with island structure induced by copper addition and oxidation.