Investigation of photoelectrocatalytic degradation mechanism of methylene blue by a-Fe2O3 nanorods array

Efficiently and thoroughly degrading organic dyes in wastewater is of great importance and challenge. Herein, vertically oriented mesoporous a-Fe2O3 nanorods array (a-Fe2O3-NA) is directly grown on fluorine-doped tin oxide (FTO) glass and employed as the photoanode for photoelectrocatalytic degradation of methylene blue simulated dye wastewater. The Ov sites on the a-Fe2O3-NA surface are the active sites for methylene blue (MB) adsorption. Electrons transfer from the adsorbed MB to Fe-O is detected. Compared with electrocatalytic and photocatalytic degradation processes, the photoelectrocatalytic (PEC) process exhibited the best degrading performance and the largest kinetic constant. Hydroxyl, superoxide free radicals, and photo-generated holes play a jointly leading role in the PEC degradation. A possible degrading pathway is suggested by liquid chromatography-mass spectroscopy analysis. This work demonstrates that photoelectrocatalysis by a-Fe2O3-NA has a remarkable superiority over photocatalysis and electrocatalysis in MB degradation. The in-depth investigation of photoelectrocatalytic degradation mechanism in this study is meaningful for organic wastewater treatment.(c) 2022 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.