Synthesis Of Molybdenum Disulfide Composites And Their Catalytic Performance For Triiodide Reduction In The Dye-sensitized Solar Cells

Dye-sensitized solar cell(DSSCs),as a new generation of photoelectric conversion device,has been considered as one of the most promising solar cells due to its high photovoltaic conversion efficiency,simple production process,and available transparency and so on.Counter electrode,which is generally conductive galss containing precious metal platinum,is the key component of the DSSCs.Although platinum electrode shows high electrocatalytic activity and superior electrical conductivity,high price and rare storage of this precious metal and instability in electrolyte containing iodine restrict large-scale production and application of dye-sensitized solar cells in the future.Therefore,research on low-cost Pt substitute is quite essential for industrialization of dye-sensitized solar cells.Because of scarce reports in existing literatures regarding the application of molybdenum disulfide and cobalt sulfide materials in the counter electrode of DSSCs.In addition,transition metal sulfides present good catalytic activity on reduction of redox couple in DSSCs.Therefore this paper studies the catalytic property of two composite materials:MoS2/Co3S4 and MoS2/CoS2.First of all,we used the hydrothermal method to synthesize the MoS2 and Co3S4 catalytic materials,respectively,and characterized them with XRD and SEM.The efficiency of the application of counter electrodes fabricated by MoS2 and Co3S4 separately in the DSSCs turned out to be merely 4.64%and 5.11%separately.Then we further synthesized MoS2/Co3S4 composite and applied the composite material in the DSSCs.By the tests of its photoelectric performance and electrochemistry impedance,and through adopting the Cyclic Voltammetry,we carried out a study on its catalytic performance and the result demonstrated that the MoS2/Co3S4 composite material shows a higher catalytic efficiency,and the highest photoelectric conversion efficiency of 6.77%is reached when the mole ratio of Mo to Co in the composite is 1:4,comparable to the efficiency of Pt of 7.14%.The result shows MoS2/Co3S4 composite is the potential alternative to Pt electrode for DSSCs.Then,we prepared composite material of MoS2/CoS2 for the application in the DSSCs to research the effect of additive amount of S on their photoelectric conversion efficiency.The result demonstrated that MoS2/CoS2 composite material will improve the photoelectric conversion efficiency to different extents.When the molar ratio of Mo,Co and S is 1:1:5,the layered MoS2 and particled CoS2 composite material shows the better electrocatalytic performance,and the MoS2/CoS2 composite Counter electrode based DSSCs achieves photoelectric conversion efficiency of 6.13%,comparable to the efficiency of Pt of 7.14%.In conclusion,this paper has studied two kinds of counter electrode materials by simple hydrothermal methods.And the two counter electrodes have reduced the cost of production and improved catalytic activity,thereby providing a new idea for the research on counter electrode materials of the DSSCs.