Nanocarbon Synthesis by Gas-liquid Plasma Using N-hexane as Raw Material

The experimental investigations of nanocarbon synthesized by pulsed gas-liquid discharge plasma in n-hexane were carried out. The process of a pulsed discharge can be roughly divided into three stages: streamer development, gap breakdown and spark discharge. Moreover, the pulsed discharge process mainly occurs in the bubble, and the active particles retained in the bubble lead to a larger area and a stronger luminescence of subsequent pulsed discharge. The color of n-hexane solution became dark brown due to the formation of nanocarbon after 30 min of plasma treatment. The main nanocarbon products are carbon quantum dots (CQDs) in the supernatant and carbon nano onions (CNOs) in the sediment. Due to the photoluminescence (PL) effect of CQDs, the supernatant showed blue fluorescence under 365 nm ultraviolet excitation. The optical emission spectra (OES) of gas-liquid plasma is mainly composed of C2, CH, Hα and Ar I, indicating that C2 and CH species are main precursors of the nanocarbon.

I. Introduction

In recent decades, nanomaterials have been attracted a lot of attention from the academic community due to their outstanding physical and chemical effects including surface effect, small size effect and macroscopic quantum tunneling effect [1], [2]. Among many nanomaterials, the synthesis and application of nanocarbon are the current research focuses. Up to now, a variety of nanocarbon have been successfully discovered and synthesized [3], such as OD fullerene, 1D carbon nanotube, 2D graphene, etc. There are many studies show that nanocarbon have excellent performance in optical, electronic, chemical, thermal and mechanical properties, making them exhibit promising applications in sensors, energy, catalysis, bio-medicine [4].