Ethanol-assisted molten salt synthesis of Bi4Ti3O12/Bi2Ti2O7 with enhanced visible light photocatalytic performance

Molten salt synthesis is an efficient method for preparation of photocatalyst. Enhancing precursor mixing effect is important. In this study, we found ethanol is important for synthsis of face-to-face type Bi 4 Ti 3 O 12 /Bi 2 Ti 2 O 7 composite photocatalyst. The prepared Bi 4 Ti 3 O 12 /Bi 2 Ti 2 O 7 (B3) composite under molar ratio of Bi:Ti of 4:3.6 displays higher photocatalytic activity compared with Bi 4 Ti 3 O 12 (B1) and Bi 2 Ti 2 O 7 (B4). The photocurrent density of B3 is 2 times higher than B1 and 1.6 times higher than B4, and B3 has smallest charge resistance between sample and solution. Combined with XPS, the study found that the higher photocatalytic activity origins from large charge transfer interface and built-in electric field (BIEF) around such interface, rathor than light absorption and dark adsorption.