Fig. 3: Additional built-in electric field introduced by gradient doping. | Nature Communications

Fig. 3: Additional built-in electric field introduced by gradient doping.

From: Gradient tungsten-doped Bi3TiNbO9 ferroelectric photocatalysts with additional built-in electric field for efficient overall water splitting

Fig. 3

a The calculated band structures of Bi3TiNbO9 with different W-doping concentrations. The calculated bandgap values are also given. The VBM (set to be 0 eV) and the Fermi level are denoted by black dotted and red dashed lines, respectively. The insets show an enlarged distribution of the Nb 4 s energy levels highlighted by the cyan dashed rectangles. The black dashed lines in the insets represent the averaged energy of the Nb 4 s levels. b The calculated density of state (DOS) of Bi3TiNbO9 with different W-doping concentrations. The DOS within an energy window from 2.0 to 3.5 eV nearby the CBM is shown in band structure plots. For the cases of B-doped Bi3TiNbO9 with doping concentration of 3.2, 6.3, and 12.5%, the local DOS value of W dopant is multiplied by a factor of 16, 8, and 4, respectively. c The band alignment of pristine Bi3TiNbO9 and W-doped Bi3TiNbO9 with different doping concentrations, by taking the Nb 4 s energy level as a reference. d Schematic diagram for the built-in electric field of Bi3TiNbO9 induced by gradient W-doping.

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