Ordered Mesostructured CdS Nanowire Arrays with Rectifying Properties

Abstract

Highly ordered mesoporous CdS nanowire arrays were synthesized by using mesoporous silica as hard template and cadmium xanthate (CdR(2)) as a single precursor. Upon etching silica, mesoporous CdS nanowire arrays were produced with a yield as high as 93 wt%. The nanowire arrays were characterized by XRD, N(2) adsorption, TEM, and SEM. The results show that the CdS products replicated from the mesoporous silica SBA-15 hard template possess highly ordered hexagonal mesostructure and fiber-like morphology, analogous to the mother template. The current-voltage characteristics of CdS nanoarrays are strongly nonlinear and asymmetrical, showing rectifying diode-like behavior.

Figure 1

aSmall-angle diffraction pattern of template-free CdS nanoarrays.bEDS pattern of the template-free CdS nanoarrays.cWAX diffraction curves of CdS nanoarrays present in SBA-15 pore channels and silica-free CdS nanoarrays

Figure 2

aNitrogen sorption isotherms of the samples successively produced in the synthesis: the SBA-15 hard template (■), CdR₂@SBA-15 composites (●) prepared by the impregnation of CdR₂into SBA-15, CdS@SBA-15 (▲) obtained from the CdR₂@SBA-15 calcined at 160 °C, and CdS-SBA-15 replicas (▼) etched by NaOH solution.bThe corresponding pore-size distribution curves ofa

Figure 3

aTEM images of the SBA-15 sample along the direction of the hexagonal pore arrangement.bTEM images of the template-free CdS sample. Insetcanddare corresponding High-magnification TEM images. Inseteis the corresponding SAED pattern ofb

Figure 4

TheI–Vcurves of CdS nanowire arrays at dark and uv-illumination condition. Insetais the SEM image of a bundle of CdS nanowire arrays on Pt electrodes. Insetbis the detailedI–Vcharacteristic of the CdS nanowire arrays under reverse bias

Figure 5

TheI–Vcurves of CdS (a) and ZnS (b) nanoarrays at dark condition