Photoelectrochemical properties of n-type NiTiO/sub 3/

Journal Article · Fri Oct 01 00:00:00 EDT 1982 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.330047· OSTI ID:7009802

Salvador, P; Gutierrez, C; Goodenough, J B

The photoelectrochemical behavior of a sintered Nb doped n-NiTiO/sub 3/ electrode in relation to the photoassisted oxidation of water has been studied. Three bands mediate the different photoprocesses observed: A conduction band (Ti/sup 4 +/:3d) several tenths of one electron volt above the H/sup +//H/sub 2/ redox level; the O/sup 2 -/:2 p/sup 6/ band about 3 eV below the conduction band; and the Ni/sup 2 +/:3d/sup 8/ ''band'' above the oxygen band that seems just to overlap the O/sub 2//H/sub 2/O level. Electronic transitions induced by UV illumination are mainly O/sup 2 -/..-->..Ti/sup 4 +/ transitions; holes photogenerated in the oxygen band move through this band, by the effect of the internal electric field, to the electrode surface where they react with water molecules with an efficiency similar to that observed in n-TiO/sub 2/ or SrTiO/sub 3/. Visible light produces Ni/sup 2 +/..-->..Ti/sup 4 +/ electronic transitions. Hole mobilities in the Ni/sup 2 +/:3d/sup 8/ ''band'' appear to be adequate for the photogenerated holes to reach the s.c. surface, where they become trapped at Ni/sup 3 +/ surface centers at an energy level too high to oxidize water efficiently. However, the geometry of the NiTiO/sub 3/ ilmenite structure makes the oscillator strength for the Ni/sup 2 +/..-->..Ti/sup 4 +/ charge transfer too weak to have an acceptable photoresponse to visible light. Therefore NiTiO/sub 3/ is not a good candidate for water photoelectrolysis in a photoelectrochemical cell. This conclusion is probably valid for other mixed-metal oxides with ilmenite structure.

• Research Organization: Instituto de Catalisis y Petroleoquimica, C.S.I.C. Serrano 119, Madrid-6, Spain
• OSTI ID: 7009802
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 53:10; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
CHEMICAL REACTIONS
DATA
DOPED MATERIALS
EFFICIENCY
ELECTRIC FIELDS
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTROLYSIS
ELEMENTS
EQUIPMENT
EXPERIMENTAL DATA
HOLES
HYDROGEN COMPOUNDS
INFORMATION
LYSIS
MATERIALS
METALS
MOBILITY
MOLECULES
N-TYPE CONDUCTORS
NIOBIUM
NUMERICAL DATA
OSCILLATOR STRENGTHS
OXIDATION
OXYGEN COMPOUNDS
PHOTOELECTROCHEMICAL CELLS
PHOTOELECTROLYSIS
SEMICONDUCTOR MATERIALS
SOLAR EQUIPMENT
SURFACES
TRANSITION ELEMENTS
WATER