Nano tumbleweed-like tungsten disulfide as a viable surrogate for platinum counter electrodes in dye-sensitized solar cells

Abstract

Tungsten disulfide (WS2), a notable member of the transition metal dichalcogenides family, has emerged as a promising candidate for energy storage and conversion applications. In this study, WS2 was synthesized via a hydrothermal method using sodium tungstate and thiourea as precursor materials, with hydroxylamine hydrochloride as the reducing agent and cetyl trimethyl ammonium bromide as a surfactant. The primary objective was to develop a cost-effective, easily synthesized, and scalable material capable of replacing platinum (Pt) in dye-sensitized solar cells (DSSCs), where Pt is both prohibitively expensive and scarce. Characterization of the synthesized WS2 was conducted through a range of physical analyses, including SEM, TEM, XRD, EDAX, FTIR, and Raman spectroscopy, which provided compelling evidence for the formation of a unique nano-tumbleweed-like structure of WS2. When used as a counter electrode (CE), the synthesized WS2 exhibited exceptional photocatalytic activity, resulting in a commendable power conversion efficiency (PCE) of 12.06 % when coupled with fluorine-doped tin oxide (FTO) plates coated with TiO2 as the photoanode, N719 as the dye, and Iˉ/I3ˉ as the liquid electrolyte. Additionally, the fabricated device underwent comprehensive electrical characterization, including cyclic voltammetry (CV), current-voltage (IV) measurements, electrochemical impedance spectroscopy (EIS), and Tafel analysis, revealing properties similar to those of Pt counter electrodes. Notably, WS2 demonstrated an open-circuit potential of 852 mV and a short-circuit current density of 28 mA/cm2, accompanied by a fill factor of 0.43 and a commendable lifetime of 15.92 ms.