Synthesis of one-dimensional metallic sulfur inside the nano-confined spaces of carbon nanotubes

Elemental sulfur, one of the most important natural resources in the chemical industry, has been used mainly for the production of sulfuric acid, vulcanization of rubber, and fertilizers. Despite its importance, sulfur has been regarded as an abundant resource due to the fact that its use is limited to being an inexpensive reagent. Here we report the synthesis of one-dimensional crystals of sulfur using the quasi one-dimensional channels of carbon nanotubes. This one-dimensional phase is confirmed by high resolution transmission electron microscopy and X-ray diffraction, revealing monatomic zigzag and linear sulfur chains inside the constrained volume of the carbon nanotubes. In addition, X-ray diffraction exhibits asymmetric Bragg peaks, indicating the formation of one-dimensional sulfur “crystals”. Most importantly, the one-dimensional sulfur crystals exhibit a metallic character at ambient pressure, whereas bulk sulfur requires ultra-high pressures exceeding ∼ 90 GPa to become metallic. These results lead us to believe that elemental sulfur has great potential to be used as a metal wire in the nanoscale, thus paving a way for future applications. 2013 (No. 260) 292–6.]