Fig. 2: Surface structure characterization of photocatalysts.

a TEM image of BTO-2. b HRTEM image of yellow frame in α1 area of (a). c HRTEM image of red frame in α2 area of (a). d SAED pattern of purple circle in β1 area of (a). e SAED pattern of blue circle in β1 area of (a). f High-resolution XPS spectra of Ti 2p. g High-resolution XPS spectra of Bi 4 f.