Structure and electronic properties of AgX (X = Cl, Br, I)-intercalated single-walled carbon nanotubes

One-dimensional silver halide crystals were grown within single-walled nanotube (SWCNT) channels from the melt using a “molten media method”. Atomic structures of the AgX@SWCNT hybrids were proposed based on high-resolution transmission electron microscopy images. It was found that AgCl intercalation results in amorphous filling of the SWCNT channels. 1D AgBr and AgI crystals intercalated into 1.34 nm SWCNTs possess the structure of a two-layer hcp   of halogen atoms arranged laterally with respect to the SWCNT axis. Electronic properties and chemical bonding in AgX@SWСNTs have been investigated by high-resolution X-ray photoelectron and near edge X-ray absorption fine structure spectroscopy (BESSY, Germany), optical absorption and Raman spectroscopy. Optical absorption spectroscopy indicates disappearance of E11S transitions between van-Hove singularities, which is caused by an effective electron exchange between AgX and the SWCNT. C 1s X-ray absorption spectra indicate a new empty level (S1) induced by charge transfer. Multi-component structure of photoemission spectra can be explained both by the variation of the work function of AgX@SWCNT hybrids and local interactions between halogen ions and carbon atoms. Raman spectroscopy performed under electrochemical charging clearly and directly demonstrated the acceptor behavior of AgX with respect to SWCNTs. Based on a whole dataset, a self-consistent picture of the AgX-SWCNT interactions is derived.