  Here, the synthesis of Molybdenum Disulphide (MoS2) flakes by means of anodic
atmospheric arc discharge is reported for the first time. The vertical
electrode configuration consisted of a compound anode (hollow graphite anode
filled with MoS2 powder) and a solid graphite cathode placed just above of the
compound anode. Arc processes were operated in pulsed mode to preferentially
evaporate the powder component from the anode and to minimize Carbon ablation.
Pulsed anodic arc discharges were conducted at 2 Hz and 10% duty cycle in 300
Torr of Helium with a peak current of 250-300 A and peak voltage of 35 V. A
probe made of Tungsten wire was placed in the vicinity of the arc column to
collect the evaporated material. The measured thickness profile was correlated
to the particle flux distribution and it was fitted by a simple model of plasma
expansion. During pulse phase, electron density was estimated around 5E22 m-3
or higher, and ion current density was of the order of 10 A/mm2. Morphology,
structure and composition of the samples were characterized by Raman
spectroscopy, atomic force microscopy (AFM), scanning electron microscopy
(SEM), transmission electron microscopy (TEM), and x-ray diffraction (XRD). The
study shows that pulsed arc discharge of the compound anode leads to moderate C
deposition combined with MoS2 deposition in the form of fragmented nanocrystals
and few atomic monolayers of MoS2. Such synthesis technique is promising to
produce new 2D nanomaterials with tailored structure and functionality thanks
to the flexibility of pulsed power.
