Silicon carbide nanotubes functionalized by transition metal atoms: A density-functional study

Single-walled carbon nanotubes (SWCNTs) functionalized by metals have great potential for applications in hydrogen storage, chemical sensors, and nanodevices, Because the exterior of single-walled silicon carbide (SiC) nanotubes has a higher reactivity than that of SWCNTs, it is highly desirable to investigate the functionalization of single-walled SiC nanotubes by transition metal atoms. In this article, we report the first study of the adsorption of a series of transition metal atoms on single-walled SiC nanotubes using density functional theory (DFT) calculations. We found that many transition metal atoms can be chemically adsorbed on the outer surface of single-walled SiC nanotubes, with binding energies ranging from 1.17 eV (for Cu) to 3.18 eV (for Pt). The physical properties of the single-walled SiC nanotubes are changed significantly by metal functionalization. Moreover, the modifications in the electronic structures of most of the metal-functionalized single-walled SiC nanotubes are little influenced by the location of the adsorption site. An exception is Ti, for which the electronic properties can vary with the adsorption site. Interestingly, the (8,0) single-walled SiC nanotube exhibits metallic characteristics when Ti adsorbs on H sites and characteristics of a smaller-band-gap semiconductor when Ti adsorbs on C sites. Our results suggest that transition metal-SiC nanotube materials could be used in interesting applications in the fabrication of gas-sensor devices, catalysts, or one-dimensional nanoconductors or nanomagnets, among others.