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 BiðNO 3 Þ 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.hydrogen production | solar energy conversion | visible light response T he development of powdered photocatalysts and semiconductor photoelectrodes for water splitting have been studied extensively in view of utilization of solar energy, since the report of the Honda-Fujishima effect (1). There are advantageous and disadvantageous points for water splitting using the powdered photocatalysts and photoelectrochemical cells. Although a powdered photocatalyst system is simple, H 2 and O 2 are produced as a mixture. In contrast to it, photoelectrochemical cells give H 2 separately from O 2 gas. Moreover, even if powdered photocatalysts do not possess band potentials suitable for water splitting (the bottom of the conduction band <0 V and the top of the valence band >1.23 V vs. NHE at pH 0), water splitting may be achieved by application of these powdered photocatalysts to photoelectrodes with applying some external bias. However, the electrical conductivity of semiconductor electrode is indispensable, resulting in that the number of the photoelectrode materials is limited.It has been reported that many metal oxides are active photocatalysts for water splitting into H 2 and O 2 stoichiometrically under UV light irradiation (2). Photoelectrodes, such as TiO 2 (1, 3, 4), SrTiO 3 (5, 6), BaTiO 3 (7), and KTaO 3 (8) have been reported for photoelectrochemical water splitting under UV light irradiation. Development of a photoelectrode material with visible light response has been sought for efficient utilization of solar energy. It has been reported that Fe 2 O 3 (9-11), WO 3 (12-14), BiVO 4 (15-24), and SrTiO 3 ∶Rh (25) of metal oxide electrodes respond to visible light. Recently, some (oxy) nitride materials such as TaON (26,27), Ta 3 N 5 (27, 28), SrN...

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

“…All the other OECs exhibited a dramatic increase in the overpotential after just a few minutes, thus indicating their instability. The activity of other OECs, such as PdO 2 [39], Pt [44], Mn 2 O 3 [58], and CoO [59] has also been demonstrated in various studies, although their long-term stability has not yet been proved.…”

Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

“…Various types of oxide-and (oxy)nitride-based n-type semiconductor materials, such as hematite [6][7][8], vanadate [9,10], the GaN:ZnO solid solution [11], nitrides [12,13], and oxynitirides [14,15] have been reported as photoanode materials. In the case of the photoanode, self-oxidation makes it difficult to utilize non-oxide materials.…”

Undoped and Ni-Doped CoOx Surface Modification of Porous BiVO4 Photoelectrodes for Water Oxidation

“…For operation in near-neutral solution (~ pH 7) cobalt-phosphate [30][31][32] and iron and nickel (oxy)hydroxides [33][34][35] have been investigated as co-catalysts for BiVO4. For more alkaline conditions (up to pH 13), transition metal oxides, such as cobalt oxides, [36][37][38][39] nickel oxides, 37 and ZnFe2O4, 40 have also been studied.…”