Photoelectrocatalytic application of a superhydrophilic exfoliated graphite supported iron doped Bi2WO6 photoanode for the degradation of Orange II dye in water

Abstract

In the quest for novel and improved photoanodes for applications in electrochemical water treatment, exfoliated graphite (EG) was used as a substrate for the preparation of Bi 2 WO 6 and superhydrophilic iron doped Bi 2 WO 6 based electrodes (photoanodes). The EG-Bi 2 WO 6 and EG-Fe doped Bi 2 WO 6 photoanodes were characterised with x-ray diffraction spectroscopy, scanning electron microscopy, diffusive reflectance spectroscopy, a goniometer (contact angle measurement), voltammetry, electrochemical impedance spectroscopy and photo-chronoamperometry. The photoanodes were applied for the solar photoelectrochemical degradation of Orange II dye in water. The results revealed that the particles of Bi 2 WO 6 and Fe doped Bi 2 WO 6 were well entrapped within the interlayers of the EG sheets. The iron doping conferred superhydrophilicity on the EG-Fe doped Bi 2 WO 6 and improved the charge separation. Exposure to Orange II dye at pH 7 and biased potential of 1.8 V resulted in the following: 95% (EG- Bi 2 WO 6 ) after 180 min and 98% degradation with EG-Fe doped Bi 2 WO 6 after 60 min. Total organic carbon removal of 49% was recorded with the EG-Bi 2 WO 6 photoanode and 68% for the EG-Fe doped Bi 2 WO 6 . Data from scavenger studies support the proposed mechanism of degradation. The EG-Fe doped Bi 2 WO 6 is reusable and lends itself to applications in photoelectrocatalytic degradation of organic pollutants in water.