  Molybdenum Disulphide (MoS2) is an interesting material which exists in
atomically thin multilayers and can be exfoliated into monolayer or a few
layers for multiple applications. It has emerged as a promising material for
development of such efficient sensors. Here, we have exfoliated and decorated
MoS2 flakes with novel, single phase High Entropy Alloy (HEA) nanoparticles
using facile and scalable cryomilling technique, followed by sonochemical
method. It is found that the decoration of HEA nanoparticles impart surface
enhanced Raman scattering effect and reduction in the work function of the
material from 4.9 to 4.75 eV as measured by UV photoelectron spectroscopy. This
change in the work function results in a schottky barrier between the gold
contact and HEA decorated MoS2 flakes as a result of drastic changes in the
surface chemical non-stoichiometry. The response to hydrogen gas is studied at
temperatures 30 to 100 oC and it shows unusual p-type nature due to surface
adsorbed oxygen species. The nanoscale junction formed between HEA and MoS2
shows 10 times increase in the response towards hydrogen gas at 80 oC. The
experimental observations are further explained with DFT simulation showing
more favourable hydrogen adsorption on HEA decorated MoS2 resulting for
enhanced response.
