Effect of Heterojunction Dynamics on Electrochemical Properties of ZnS/MoS2 Type-II Nanocomposite for Photovoltaic Application

In the present work, ZnS/MoS2 nanocomposite has been synthesized by hydrothermal route. X-ray diffraction analysis revealed ZnS and MoS2 phases, showing the crystallite size of 19.5 and 9.25 nm from W-H and S-S plots, respectively. The lattice parameters of MoS2 and ZnS were found to be a = b = 3.79 & Aring;, c = 12.4 & Aring; and a = b = 3.2 & Aring;, and c = 9.5 & Aring;, respectively. The dislocation density, stacking fault and strain from W-H and S-S plots were found to be 4.1 x 10(-4), 2.4 x 10(-3), -1.2 x 10(-3 )and -2.4 x 10(-2), respectively. The absorbance peaks of the nanocomposite were observed at 209, 246 and 320 nm revealing a band gap of 3.3 eV with refractive index of 2.32. Scanning electron microscopy and transmission electron microscopy imaging demonstrated ZnS nanoparticles over MoS(2 )sheets with an average particle size of 45.9 and 23.8 nm, respectively. In cyclic voltammetry analysis, pure ZnS and nanocomposite showed maximum oxidation current of 0.25 and 0.51 mA, respectively. Electrochemical impedance spectroscopy analysis revealed the presence of Warburg diffusion with a high exchange current density of 2.5 mA along with electrolyte's and working electrode's resistance to be 1000 Omega and 100 Omega, respectively. Charge transfer resistance, Warburg impedance, electrical double layer capacitance and film's capacitance was found to be 10 Omega, 1000 Omega<middle dot>s(-1/2), 100 mu F and 1 mu F, respectively.