Enhancing photoelectrochemical activity of nanocrystalline WO_3 electrodes by surface tuning with Fe(Ⅲ)

摘要

Tungsten oxide (WO_3) photoelectrodes with the surface tuned by Fe(Ⅲ) for photo-electrochemical water splitting were successfully synthesized. Nanostructured WO_3 films were prepared using doctor blade method, then a facile and economical deposition-annealing process was employed to fabricate Fe(Ⅲ) modified WO_3 films. The resulting composite's structural and optical properties were analyzed by SEM, EDX, XRD, UV-Vis spectrometry and XPS. The photoelectrochemical properties were evaluated by photocur-rent density under 500 W Xe lamp with an intensity of 100 mW/cm~2. The Fe(Ⅲ) modified WO_3 electrode exhibited a larger photocurrent than the pure WO_3 electrode. Significantly, the optimized Fe(Ⅲ) modified WO_3 film achieved the maximum photocurrent density of 1.18 mA/cm~2 at 0.8 V vs. Ag/AgCl in the 0.2 M Na_2SO_4 .The enhanced photocurrent was attributed to the extension of the light response and the electron hole separation at the interface Fe(Ⅲ)/WO_3 which was confirmed by Mott-Schottky and electrochemical impedance spectroscopy.