Facile fabrication of an efficient BiVO 4 thin film electrode for water splitting under visible light irradiation

Abstract

An efficient BiVO 4 thin film electrode for overall water splitting was prepared by dipping an F-doped SnO 2 (FTO) substrate electrode in an aqueous nitric acid solution of Bi(NO 3 ) 3 and NH 4 VO 3 , and subsequently calcining it. X-ray diffraction of the BiVO 4 thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO 4 was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO 4 film with 300–400 nm of the thickness. The BiVO 4 thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag/AgCl. Modification with CoO on the BiVO 4 electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO 4 thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H 2 and O 2 was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO 3 ∶Rh photocathode and the BiVO 4 photoanode.