PVP-assisted synthesis of nanostructured transparent WO3 thin films for photoelectrochemical water splitting

Abstract

The transparent tungsten trioxide (WO3) films having nanostructured porous morphology and monoclinic crystal phase were prepared with the assistance of polyvinylpyrrolidone (PVP) and ammonium metatungstate (AMT) by spin coating and screen printing methods. By controlling the atomic ratio of pyrrolidone ring nitrogen (PRN) from PVP to W from AMT, the porous, photocatalytically active and transparent nanoparticulate films of WO3 can be synthesized. The PRN/W ratio was found to affect the crystallite size of WO3. The spin-coated WO3 photoanode prepared with the PRN/W atomic ratio of 0.25 demonstrated optimum photoelectrochemical (PEC) performance in 0.5M H2SO4 under 1 sun illumination. The enhancement can be attributed to the high crystallinity, porosity, optimum film thickness with reduced defects in the films. In contrast, the screen-printed WO3 films showed the transmittance as high as 60%. Such transparent films could be the potential candidates for use in tandem configuration for water splitting application.