Figure 1. (a) Schematic diagram of fabrication route of ZnS-ZnO nanotubes/carbon cloth (ZSONT/CC). SEM images of (b) carbon cloth (CC), (c) ZnO nanorods on carbon cloth (ZnO/CC), (d) ZnS@ZnO nanocables on carbon cloth (ZnS-ZnO/CC), and (e) ZSONT/CC.

The synthesis process of ZnS-ZnO nanotubes/Carbon Cloth (ZSONT/CC) was illustrated in Figure 1a . We first introduced ZnO nanoarrays on the surface of carbon cloth, then formed ZnS-ZnO nanoarrays/Carbon Cloth by ion-exchange method, the following acid treatment led to the formation of the final product ZSONT/CC. The resulted carbon cloth was found to be similar to its starting counterpart in SEM at low magnification (Fig. 1b-e ). However, at higher magnifications, the surface of each of carbon fiber (in the cloth) appears modified with one-dimensional nanostructures. Figure 1c, 1d, and 1e disclosed the morphological evolution from ZnO/CC, to ZnS-ZnO/CC and to ZnS-ZnO nanotubes (ZSONT)/CC. From the scanning electron microscopy (SEM) image of ZnO/CC (Fig. 1c ), dense nanoarrays were found on the carbon cloth and the diameter of the individual nanorods is ~100 nm. The introduction of ZnS to ZnO/CC led to little change in nanorods’ morphology, but the diameter of the NRs increased to ~150 nm (Fig. 1d ). The acid treatment resulted in a tubular structure with a diameter of ~150 nm (Fig. 1e ). As can be seen from the moderately magnified images of ZnO/CC and ZnS-ZnO/CC, they uniformly grew on the entire carbon fiber.