Ultrasonically assisted preparation of molybdenum sulfide/graphitic carbon nitride nanohybrid as counter electrode material for dye-sensitized solar cell

Graphitic carbon nitride (g-C3N4) has special semiconducting properties which make it candiate for several catalytic processes. The subject of using g-C3N4 for electrochemical studies such as energy storage and conversion is important aspect which may be considered for further investigations. In this research, nanostructured molybdenum sulfide (MoS2)/g-C3N4 was synthesized through sonochemical method and used as active material for the fabrication of counter electrode (CE) in dye-sensitized solar cell (DSSC). MoS2 was synthesized by hydrothermal method and g-C3N4 was prepared using thiourea precursor through condensation polymerization method. Then, two materials were combined under ultrasonic irradiation to obtain nanostructured MoS2/g-C3N4. For preparation of CE, the nanohybrid was coated onto fluorine doped tin oxide (FTO) glass. Structural characterization of MoS2 /g-C3N4 nanohybrid was perfoemed uisng X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The MoS2 /g-C3N4 CE displays higher current density and lower overpotentials for redox reactions of triiodide/iodide (I3-/I-) than MoS2 and g-C3N4 CEs and has high catalytic activity and low charge transfer resistance. The photoanode was prepared using a transparent layer of 20 nm sized TiO2 nanoparticles and a reflective layer of 300 nm sized TiO2 particles pasted on FTO and then sensitized with immersion in 0.4 mM N719 dye. The fabricated DSSC based on MoS2/g-C3N4 CE was investigated using J-V analysis under AM 1.5 irradiation (100 mW cm−2) and a maximum power conversion efficiency of 6.69% was obtained. The results showed that the idea of using g-C3N4 in the preparation of new hybrid materials for CEs can be considered to improve the performance of DSSC.