Rapid Screening by Scanning Electrochemical Microscopy (SECM) of Dopants for Bi2WO6 Improved Photocatalytic Water Oxidation with Zn Doping

Bi 2 WO 6 microelectrode arrays on FTO glass substrates were fabricated by a picoliter solution dispensing technique using Bi(NO 3 ) 3 as the Bi source and (NH 4 ) 6 H 2 W 12 O 40 as the W source in ethylene glycol. The scanning electrochemical microscope modified by using an optical fiber in place of an ultramicroelectrode was employed for rapid screening of the Bi 2 WO 6 arrays and to investigate the effect of 12 different dopants on the photocatalytic oxidation of SO 3 2– . Among the different dopant compositions, addition of 12% Zn showed a photocurrent enhancement of up to 80% compared with that of the pure Bi 2 WO 6 . This result was further confirmed with bulk electrode studies for SO 3 2– and water oxidation. UV–vis absorption, electrochemical impedance spectroscopy, scanning electron microscopy, and X-ray diffraction studies were carried out with the photocatalysts to elucidate the role of Zn in the bulk semiconductors. Absorbed photon-to-current efficiency and incident photon-to-current efficiency determinations further confirm the enhancement of photoelectrochemical behavior upon addition of Zn to Bi 2 WO 6 photocatalysts.