TY - JOUR
T1 - Role of Sn2+ in the band structure of SnM2O 6 and Sn2M2O7 (M = Nb and Ta) and their photocatalytic properties
AU - Hosogi, Yasuhiro
AU - Shimodaira, Yoshiki
AU - Kato, Hideki
AU - Kobayashi, Hisayoshi
AU - Kudo, Akihiko
PY - 2008/2/26
Y1 - 2008/2/26
N2 - The photocatalytic properties of metal oxides consisting of Sn2+ with a 5s2 configuration were studied to find new visible light responsive photocatalysts. The band gaps of Ca2Ta2O 7, Sn2Ta2O7, and Sn 2Nb2O7 were found to be 4.8, 3.0, and 2.3 eV, respectively. Density functional calculations revealed that the valence band levels formed with Sn 5s orbitals were more negative than those with O 2p orbitals. The result is that niobates and tantalates containing Sn2+ have narrow band gaps compared with typical niobates and tantalates. SnNb 2O6 showed photocatalytic activity for H2 and O2 evolution from aqueous solutions containing sacrificial reagents (methanol and Ag+) under visible light irradiation (λ > 420 nm). Moreover, the photocatalytic activity of SnNb2O6 depended on the material used as the Sn source. SnNb2O6 synthesized from Sn3O2(OH)2 showed higher activity for H2 and O2 evolution than that synthesized from commercial SnO, which included a small amount of SnO2. SnNb 2O6 synthesized from Sn3O2(OH) 2 showed activity for O2 evolution under visible light, even without IrO2 as a cocatalyst, whereas that synthesized from commercial SnO showed activity under irradiation only when an IrO2 cocatalyst was loaded. The activity of SnNb2O6 synthesized from SnO was improved by IrO2 cocatalyst loading.
AB - The photocatalytic properties of metal oxides consisting of Sn2+ with a 5s2 configuration were studied to find new visible light responsive photocatalysts. The band gaps of Ca2Ta2O 7, Sn2Ta2O7, and Sn 2Nb2O7 were found to be 4.8, 3.0, and 2.3 eV, respectively. Density functional calculations revealed that the valence band levels formed with Sn 5s orbitals were more negative than those with O 2p orbitals. The result is that niobates and tantalates containing Sn2+ have narrow band gaps compared with typical niobates and tantalates. SnNb 2O6 showed photocatalytic activity for H2 and O2 evolution from aqueous solutions containing sacrificial reagents (methanol and Ag+) under visible light irradiation (λ > 420 nm). Moreover, the photocatalytic activity of SnNb2O6 depended on the material used as the Sn source. SnNb2O6 synthesized from Sn3O2(OH)2 showed higher activity for H2 and O2 evolution than that synthesized from commercial SnO, which included a small amount of SnO2. SnNb 2O6 synthesized from Sn3O2(OH) 2 showed activity for O2 evolution under visible light, even without IrO2 as a cocatalyst, whereas that synthesized from commercial SnO showed activity under irradiation only when an IrO2 cocatalyst was loaded. The activity of SnNb2O6 synthesized from SnO was improved by IrO2 cocatalyst loading.
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U2 - 10.1021/cm071588c
DO - 10.1021/cm071588c
M3 - Article
AN - SCOPUS:40549124392
SN - 0897-4756
VL - 20
SP - 1299
EP - 1307
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 4
ER -