Surface properties of Ta2O5 layers prepared on SBA-15

Ta 2 O 5 layer was prepared onto SBA-15 (Ta 2 O 5 /SBA-5) with Ta ethoxide precursor. The surface properties of Ta 2 O 5 /SBA-5 was the same as those of mesoporous Ta 2 O 5 , possessing electron accepting sites and hydrophobicity, but the structural stability upon thermal treatment was improved due to the presence of SBA-5. The drastic blue shift in UV–vis absorption band was observed when the phase of Ta 2 O 5 became thinner. Accordingly, band gaps of Ta 2 O 5 samples increased from 4.0 (nonporous Ta 2 O 5 ) to 4.3 eV (mesoporous Ta 2 O 5 , 2.3 nm wall thickness), and further increased to 4.9 eV for thin-layered Ta 2 O 5 /SBA-5 (0.5 nm Ta 2 O 5 layer). Thus, stable activity for photocatalytic water decomposition was not observed over thin-layered Ta 2 O 5 /SBA-5.