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

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 Bi2WO6 and superhydrophilic iron doped Bi2WO6 based electrodes (photoanodes). The EG-Bi2WO6 and EG-Fe doped Bi2WO6 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 Bi2WO6 and Fe doped Bi2WO6 were well entrapped within the interlayers of the EG sheets. The iron doping conferred superhydrophilicity on the EG-Fe doped Bi2WO6 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-Bi2WO6) after 180 min and 98 % degradation with EG-Fe doped Bi2WO6 after 60 min. Total organic carbon removal of 49 % was recorded with the EG-Bi2WO6 photoanode and 68 % for the EG-Fe doped Bi2WO6. Data from scavenger studies support the proposed mechanism of degradation. The EG-Fe doped Bi2WO6 is reusable and lends itself to applications in photoelectrocatalytic degradation of organic pollutants in water.