TY - JOUR
T1 - The roles of surface-doped metal ions (V, Mn, Fe, Cu, Ce, and W) in the interfacial behavior of TiO2 photocatalysts
AU - Chang, Su-Min
AU - Liu, Wei szu
PY - 2014/9
Y1 - 2014/9
N2 - Six types of transition metal ions, including V, Mn, Fe, Cu, Ce, and W, are doped into the surface lattice of TiO2 powders, and their roles in the charge trapping, recombination, interfacial transfer, and photocatalytic activity are systematically studied. The surface-doped TiO2 powders exhibit photocatalytic activity in the order of Fe/TiO2>Cu/TiO2>V/TiO2>W/TiO2>Ce/TiO2>Mn/TiO2. While the Fe, Cu and V ions improve the activity, the W, Ce, and Mn ions cause detrimental effects. The different influences are associated with their energy levels, coordination numbers and electronegativity. The surface-doped ions trap charge carriers and interact with adsorbates to provide alternative pathways for interfacial charge transfer. The Fe and Cu ions inhibit defect-mediated annihilation, facilitating interfacial charge transfer in terms of d-d transitions and thermally induced de-trapping. The Mn ions, which introduce both occupied and unoccupied states in the mid-band-gap region, in contrast, trap holes and electrons to severely consume charge carriers via intra-atomic relaxation. The Ce and W ions, which have high coordination numbers and electronegativity, strongly bond the O2- radicals, thus limiting charge utilization as well as photocatalytic performance.
AB - Six types of transition metal ions, including V, Mn, Fe, Cu, Ce, and W, are doped into the surface lattice of TiO2 powders, and their roles in the charge trapping, recombination, interfacial transfer, and photocatalytic activity are systematically studied. The surface-doped TiO2 powders exhibit photocatalytic activity in the order of Fe/TiO2>Cu/TiO2>V/TiO2>W/TiO2>Ce/TiO2>Mn/TiO2. While the Fe, Cu and V ions improve the activity, the W, Ce, and Mn ions cause detrimental effects. The different influences are associated with their energy levels, coordination numbers and electronegativity. The surface-doped ions trap charge carriers and interact with adsorbates to provide alternative pathways for interfacial charge transfer. The Fe and Cu ions inhibit defect-mediated annihilation, facilitating interfacial charge transfer in terms of d-d transitions and thermally induced de-trapping. The Mn ions, which introduce both occupied and unoccupied states in the mid-band-gap region, in contrast, trap holes and electrons to severely consume charge carriers via intra-atomic relaxation. The Ce and W ions, which have high coordination numbers and electronegativity, strongly bond the O2- radicals, thus limiting charge utilization as well as photocatalytic performance.
KW - Charge recombination
KW - Electronic structures
KW - Interfacial charge transfer
KW - Photocatalytic activity
KW - Surface doping
UR - http://www.scopus.com/inward/record.url?scp=84919414477&partnerID=8YFLogxK
U2 - 10.1016/j.apcatb.2014.03.044
DO - 10.1016/j.apcatb.2014.03.044
M3 - Article
AN - SCOPUS:84919414477
SN - 0926-3373
VL - 156-157
SP - 466
EP - 475
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
ER -