Photoelectrochemical properties and photocatalytic activity of nitrogen-doped nanoporous WO3 photoelectrodes under visible light

Abstract In the present work, nitrogen-doped tungsten oxide (WO 3 ) nanoporous photoelectrode was studied by photoelectrochemical and photocatalytic methods in order to evaluate the photoactivity and the possibility of its application in solar photocatalysis. WO 3 nanoporous photoelectrodes were prepared by anodization of tungsten foil in NH 4 F/(NH 4 ) 2 SO 4 electrolytes, followed by annealing in NH 3 /N 2 to incorporate N as a dopant. The crystal structure, composition and morphology of pure and nitrogen doped WO 3 were compared using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). The results indicate that nitrogen can be doped successfully into WO 3 nanoporous photoelectrodes by controlling annealing temperature. Incident photon to current efficiency measurements carried out on PEC cell with N-doped WO 3 nanoporous photoelectrodes as anodes demonstrate a significant increase of photoresponse in the visible region compared to undoped WO 3 nanoporous photoelectrodes prepared at similar conditions. In particular, the photocatalytic and photoelectrocatalytic activity under visible light irradiation for newly synthesized N-doped WO 3 nanoporous photoelectrodes were investigated by degradation of methyl orange. The photoelectrocatalytic activity of N-doped WO 3 nanoporous photoelectrodes was 1.8-fold enhancement compared with pure WO 3 nanoporous photoelectrodes.