Synthetic modulation of layer dependent mos2 nanosheet and enhanced electrochemical HER and ORR kinetics through zinc doping

Abstract

The works presented in the thesis “Synthetic modulation of layer dependent MoS2 nanosheet and enhanced electrochemical HER and ORR kinetics through Zinc doping” has its prime focus on two things: first, to synthesize 2H-MoS2 nanosheet and separate its different layers without metal intercalation, and second, to measure the HER and ORR kinetics of different concentrations of Zinc doped in MoS2. Due to both its novel physical properties and its potential for use, the two-dimensional nanomaterial MoS2 is extremely fascinating. The utilisation of liquid exfoliation, a vital production method, is constrained by our inability to quickly and correctly monitor nanosheet size, thickness, or concentration. We have developed a simple and flexible centrifugation strategy based on Band sedimentation to rapidly sort liquid-suspended TMDs according to their mass using a conventional tabletop centrifuge. This procedure resulted in a range of fractions (samples) with distinctly different extinction spectra. While the measurements of size and thickness are based on the influence of edges and quantum confinement on the optical spectra, the concentration measurement is based on the size independence of the low-wavelength extinction coefficient. The controllability of concentration, size, and thickness that results makes it simpler to produce dispersions with predetermined characteristics, including high monolayer content. These techniques are generic and can be used to a wide range of two-dimensional materials, including WS2, MoSe2, and WSe2. For the advancement of future energy, non-noble metal electrocatalysts with superior performance and financial advantages for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are essential. MoS2 based materials in particular, which are two-dimensional transition-metal sulphides, are thought to be excellent substitute catalysts for the HER and ORR, where doping engineering has shown to be an efficient technique to modify their electrocatalytic activity. In this work, we have reported that Zn-doped MoS2 exhibits increased electrochemical activity when compared to pure MoS2. The produced Zn-doped MoS2 (MoS2-30) exhibits outstanding HER and ORR performance. Doping engineering thus offers an effective way to increase the intrinsic activity of transition-metal sulphides and may aid in the creation of nonprecious electrocatalysts for HER and ORR.