Study of enhancing photocatalytic activity of solvothermal grown MoS2 nanocrystals under visible light irradiation by the influence of hydrogen peroxide

Abstract

In this article, two-dimensional molybdenum sulfide has been synthesized by simple and conventional solvothermal methods and the combined effect of MoS2 nanocrystals and hydrogen peroxide in photocatalytic degradation of methylene blue (MB) in water has been investigated under visible light. Synthesized MoS2 nanocrystals have been characterised by FEG-TEM, FE-SEM, XRD, Raman, FTIR, UV–Vis absorption, PL and TCSPC studies. FEG-TEM and FE-SEM images confirm nanosheets/nanoflowers like morphology and Raman & XRD patterns confirm the 2H-MoS2 phase. Layer-dependent absorption spectra and its Tauc plot were studied and the calculated band gap are found to be 1.73 eV and 1.43 eV for a few layers, bulk MoS2 respectively. This layer-dependent band gap energy is also verified by calculating electronic band structure for mono-layer, bi-layer and bulk MoS2 through density functional theory (DFT). The calculated average lifetime of in MoS2 is 1.5 ns. The kinetic study of the degradation of MB dye with MoS2 in the presence of H2O2 showed complete degradation of MB within 20 min. Whereas, pure MoS2 and H2O2 showed 28.27 % and 89.2 % degradation of MB within 210 min time intervals respectively. Thus, these results show MoS2 has good photocatalytic activity in the presence of H2O2.