WO3 Catalyst Being Prepared by Ammonium Paratungstate for DSSCs Applications

Dye-sensitized solar cells (DSSCs), as a renewable energy source, have attracted considerable attention due to their unparalleled merits including low cost, choice of color, light weight, packing technology, environmental compatibility, and acceptable photoelectric conversion efficiency (PCE).

Tungsten (W)-based compounds (oxides, nitrides, carbides and hybrids) as CEs were widely tested for use in the DSSC system because of their excellent properties, such as various sources, low cost, and notable electrocatalytic activity. Recently, WO3 catalyst had been prepared successfully by ammonium paratungstate (APT) for DSSCs applications. The synthesis method of the WO3 catalyst is as following steps:

WO3 nanoparticles were prepared via a simple chemical method. Briefly, 1.53 g ammonium paratungstate (99.5% purity) was dissolved in 50 mL distilled water, and aniline (Alfa, ≥99%) was added. Subsequently, the pH was adjusted to 4-5 to yield a white precipitate. After stirring at 40 °C for 6 h, the precipitate was filtrated, washed with water, and dried at 60 °C for 3 d. Finally, WO3 was obtained by sintering the precipitate at 700 °C for 6 h under a nitrogen atmosphere.

The purchased TiO2 film (P25, Degussa, Germany) was annealed at 500 °C for 30 min under air and then cooled to 120 °C. The resulting TiO2 film was immersed in a 0.5 mM solution of N719 dye in acetonitrile/tert-butyl alcohol (1:1 volume ration) for 24 h to obtain the dye-sensitized TiO2 photoanode. WO3, with a ZrO2 pearl (6 g) were dispersed in isopropanol (5 mL) and milled for 4 h. The obtained solutions were sprayed onto an FTO glass substrate (Asahi Glass, type-U, 14 Ωsq−1 Japan) using an airbrush. The FTO glass substrate, coated with a WO3 film was annealed under N2 at 400 °C for 30 min in a tube furnace, and the expected W-based CEs were obtained. The Pt electrode was prepared by pyrolysis of a H2PtCl6 isopropyl alcohol solution at 500 °C for 30 min under air. A DSSC with an active area of 0.16 cm2 was assembled using a sensitized TiO2 photoanode, a CE, and I−/I3− electrolyte.

In summary, WO3 catalyst has been prepared successfully by ammonium paratungstate (APT) for DSSCs applications. The DSSC assembled with WO3 CEs exhibited a PCE of 5.20%. The superior electrocatalytic activities is beneficial from of band gap of WO3(1.7 eV). In addition, the W/O ratio (1:2.72) in W18O49, the W/O ratio (1:3) in WO3, Higher W/O or W/N ratio leads to improved electrocatalytic activity of CEs in DSSCs.

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