Photoelectrocatalytic activity of perovskite YFeO₃/carbon fiber composite electrode under visible light irradiation for organic wastewater treatment

Background: A considerable amount of azo dye wastewater is generated from textile industry every day, which jeopardizes human health and environment. To treat azo dye-containing wastewater in visible-light environment, a perovskite YFeO₃/carbon fiber (CF) electrode was developed. Methods: A sol-gel process combined with calcination was adopted to synthesize YFeO₃ catalysts, and the composite electrode was fabricated using a facile dip-coating method. Significant findings: The YFeO₃ powder that was calcined at 700 °C consisted of mixed hexagonal and orthorhombic phases with crystallite sizes of 15–30 nm. The particles tended to aggregate, forming a porous structure, and they exhibited a photocatalytic degradation capability for Reactive Black 5 (RB5) dyes. Notably, the YFeO₃/CF composite electrode enabled significant photoelectrocatalytic activity over RB5 under visible light irradiation, with a removal efficiency of 99% in a 60 min treatment. In addition, the composite electrode demonstrated its high stability during the repeated treatments. The synergetic effect of photo- and electrocatalysis accounted for breaking the N=N bonds, as well as the benzene and naphthalene structures of RB5, resulting in a favorable pollutant degradation. Moreover, the photoelectrocatalytic treatment system kinetics followed a pseudo-first-order rate equation, corresponding to a single-molecule reaction. The improved photoelectrocatalytic activity of the composite electrode can be attributed to the reduced surface and charge transfer resistances during the photoelectrocatalysis process.