Fig. 4. (a) GCMS spectra for desorbed compounds on ZnO nanowires, ZnO/CuO nanowires and (Cu, Zn)O nanowires. (b) CuO shell thickness dependent conversion ratio of nonanal to (E)-2-hepthyl-2-undecenal. The inset shows its surface Cu ratio dependence. (c) TPDMS profiles of desorbed compounds on ZnO nanowires, ZnO/CuO nanowires and (Cu, Zn)O nanowires, which are evaluated at m/z 98. For ZnO/CuO nanowires, the CuO shell thickness is 10 nm. For (Cu, Zn)O nanowires, the CuO shell thickness is varied in the range of 3–20 nm. ‘NWs’ represents ‘nanowires’.