Effects of precursor molecules on polyyne formation by arc discharge between two copper electrodes

Abstract Polyynes were synthesized by arc discharge between two copper electrodes in alkanes for the first time. The as-grown polyyne samples were separated through high-performance liquid chromatography and the size-selected polyynes C 2n H 2 (n = 4–6) were investigated by surface-enhanced Raman scattering spectroscopy. The formation rate of polyynes has been found to increase with rising carbon-hydrogen ratio of the alkanes, and the alkanes affect the length of polyyne chains. The reaction enthalpy from alkane to C 2 radicals decreases with increasing carbon-hydrogen ratio, which causes the energy consumption in the whole reaction to differ and leads to different formation rates.