Oxidation Synthesized CuO Nanowires for Gas Sensing Applications K. Sawicka, M. Karadge, A K. Prasad and P I. Gouma Materials Science & Engineering, 314, Old Engineering Building, State University of New York, Stony Brook, NY 11794-2275. One dimensional nanoscale materials are currently of interest due to their unique properties. CuO nanowires (transition metal oxide, with indirect band gap of charge transfer nature [1]) can be potentially applicable in gas sensing (CO, NO 2 , H 2 S) [2,3], magnetic storage media [4], nanodevices [5], catalysis [6], and in CuO based superconductors [7]. However detailed studies on synthesis of CuO nanowires/whiskers are few. The CuO wires/whiskers can be fabricated by thermal evaporation [8], thermal decomposition of precursors [9], self catalytic growth [10], electrospinning [11] etc. This paper describes an improvement over the oxidation synthesis (thermal evaporation and oxidation) of CuO nanowires for gas sensing applications. It was previously observed [8] that CuO nanowires can be grown by heating copper substrates in air. Also, it is known that organic nanowires on the copper substrate can nucleate growth of copper nanowires/whiskers by diffusing through the organic nanotubes [12]. We have implemented the aforesaid facts for growing a high density of CuO nanowires on copper grids. Figure 1 shows the CuO nanowires grown on 50 µm thick formvar copper grid heat treated in air at 500 o C for 8 hrs. Further, to improve the density of nanowires, MoO3 doped PVP (poly-vinyl-pyrrolidone) nanofibers were deposited by electrospinning followed by heat treating at 500 o C for 8 hrs. It was observed that indeed there is a significant improvement in the density of the nanowires grown on the thickness side of the Cu grids as shown in figures 2 and 3. Studies on effects of oxygen concentration on the size distribution of the CuO nanowires are under investigation. Also, a two step process involving heat treating in vacuum allowing for diffusion of copper in the PVP nanowires followed by oxidation in air is under development for increasing the density and connectivity between the CuO nanowires. The optimized process parameters will be utilized to design (figure 4) and fabricate CuO based gas sensors. References 1. F. Marabelli et.al., Phys. Rev. B, 52, (1995), 1433. 2. A. Cruccolini et.al., Sensors & Actuators B, In Press. 3. M. Frietsch et.al., Sensors & Actuators B, 65 (2000), 379. 4. S. Yang et.al., Appl. Phys. Lett., 83, 18, (2003), 3746. 5. C-T. Hsieh et.al., Appl. Phys. Lett., 83, 16, (2003), 3383. 6. J. Reitz et.al., J. Am. Chem. Soc., 120, (1998), 11467. 7. A. MacDonald, Nature, 414, (2001), 409. 8. X. Jiang at.al., Nano Letters, 2, 12, (2002), 1333. 9. C. Xu et.al., Mater. Res. Bull., 37, (2002), 2365. 10. C-T. Hsieh et.al., Appl. Phys. Lett., 82, 19, (2003), 3316. 11. H. Guan et.al., Inorganic Chem. Comm., 6, (2003), 1409. 12. H. Hwang at.al., Solid State Comm., 129, (2004), 687. Microsc Microanal 10(Suppl 2), 2004 Copyright 2004 Microscopy Society of America DOI: 10.1017/S1431927604886033 360