Fig. 1. (Color online) SEM images of (a) BFO and (b) Au/BFO. (c) XRD spectra of BFO and Au/BFO. (d) XPS spectra of BFO.

Fig. 2. (Color online) (a) J–V, (b) J–t and (c) IPCE curves of BFO and Au/BFO. (d) Photocurrent of the Au/BFO and positively or negatively poled Au/BFO under –0.4 V vs Ag/AgCl.

Fig. 3. (Color online) (a) Absorbance spectra, (b) light harvesting efficiencies (η_LHE), (c) electron flux and (d) charge separation efficiency (η_separation) of BFO and Au/BFO.

Fig. 4. (Color online) (a) The PL spectra and (b) transient PL decay spectra of BFO and Au/BFO.

Fig. 5. (Color online) (a) Nyquist plots of electrochemical impedance spectra and (b) Mott-Schottky plots of BFO and Au/BFO.

Fig. 6. (Color online) (a) Schematic of work function of FTO, Au and BFO. Schematic of the electron-transfer mechanism of (b) FTO/BFO and (c) FTO/Au/BFO. The photogenerated carrier transfer mechanism of Au/BFO photoelectrode under (d) no poling, (e) positive poling and (f) negative poling.