Letters to the Editor In situ synthesis of super-long Cu nanowires inside carbon nanotubes with coal as carbon source

Nano-sized copper wires have received considerable attention because of their potential applications in next generation electronic nanodevices in future [1,2]. Up to now, a number of approaches including vapor depositions [1], template synthesis [2,3], solution-phase reactions [4,5] and vapor–solid reaction growth (VSRG) [6] have been developed for making copper nanowires. Despite of the great progresses, some tough problems related to the quality of copper nanowires such as poor oxidation resistance and crystallinity, short length, and nonlinear morphology still need to be addressed [1–7]. Carbon nanotubes (CNTs) are believed to be a good template for making Cu nanowires with perfect 1D morphology and good stability, and this idea has been tested by arc discharge in hydrogen [8] or microwave plasma-assiste