Efficient Photoelectrochemical Water Splitting by Tailoring MoS2/CoTe Heterojunction in a Photoelectrochemical Cell

Abstract

Solar energy conversion through photoelectrochemical water splitting (PEC) is an upcoming promising technique. MoS2/CoTe heterostructures were successfully prepared and utilized for PEC studies. MoS2 and CoTe were prepared by a hydrothermal method which were then ultrasonicated with wt. % ratios of 1:3, 1:1 and 3:1 to prepare MoS2/CoTe (1:3), MoS2/CoTe (1:1) and MoS2/CoTe (3:1) heterostructure, respectively. The pure materials and heterostructures were characterized by XRD, UV–vis-DRS, SEM, XPS, PL and Raman spectroscopy. Photoelectrochemical measurements were carried out by linear sweep voltammetry and electrochemical impedance spectroscopic measurements. A maximum photocurrent density of 2.791 mA/cm2 was observed for the MoS2/CoTe (1:1) heterojunction which is about 11 times higher than the pristine MoS2. This current density was obtained at an applied bias of 0.62 V vs. Ag/AgCl (1.23 V vs. RHE) under the light intensity of 100 mW/cm2 of AM 1.5G illumination. The enhanced photocurrent density may be attributed to the efficient electron–hole pair separation. The solar to hydrogen conversion efficiency was found to be 0.84% for 1:1 MoS2/CoTe, signifying the efficient formation of the p-n junction. This study offers a novel heterojunction photocatalyst, for PEC water splitting.