A study on surfactant-free growth of silver-carbon nanocables by H_2SO_4-mediated hydrothermal process

摘要

We study the one-pot facile hydrothermal growth of ultralong silver-carbon (Ag-C) nanocables with Ag nanowires as the cores and carbon as the sheaths through the mediation of H_2SO_4 and without using an organic surfactant. In the investigation, Ag-C nanostructures were systematically and extensively examined as a function of both temperature and H_2SO_4 concentration to locate the optimal conditions for preparing ultralong, robust, and uniform Ag-C coaxial nanocables at T = 180 ℃ and 0.5 M H_2SO_4. The characterization clearly demonstrated a simple, efficient, and surfactant-free synthesis of Ag-C nanocables. In the hydrothermal process, glycerol acts as both reducing agent and carbon source, while H_2SO_4 mediates the directional growth of the silver nanowire core and assists the deposition of carbon. Moreover, the nanocables manifest unusual ferromagnetism at room temperature and a plausible mechanism of forming Ag-C nanocables was proposed as a result of the chain-like hydrogen sulfate compounds owing to the H_2SO_4 mediation.