Synthesis
of Tin Catalyzed Silicon and Germanium Nanowires
in a Solvent–Vapor System and Optimization of the Seed/Nanowire
Interface for Dual Lithium Cycling
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Abstract
Silicon and germanium nanowires are
grown in high density directly
from a tin layer evaporated on stainless steel. The nanowires are
formed in low cost glassware apparatus using the vapor phase of a
high boiling point organic solvent as the growth medium. HRTEM, DFSTEM,
EELS, and EDX analysis show the NWs are single crystalline with predominant
⟨111⟩ growth directions. Investigation of the seed/nanowire
interface shows that in the case of Si an amorphous carbon interlayer
occurs that can be removed by modifying the growth conditions. Electrochemical
data shows that both the tin metal catalyst and the semiconductor
nanowire reversibly cycle with lithium when the interface between
the crystalline phases of the metal and semiconductor is abrupt. The
dually active nanowire arrays were shown to exhibit capacities greater
than 1000 mAh g<sup>–1</sup> after 50 charge/discharge cycles