Cu-Fe LDHs/Bi2WO6 composite for superior photo-Fenton Rhodamine B removal through combination of photogenerated electrons and multivalent bimetal redox for accelerating Fe3+/Fe2+ cycles

In this work, typical refractory pollutant Rhodamine B (RhB) was effectively degraded by Cu-Fe LDHs/Bi2WO6 composite in the photo-Fenton process. The hydrothermal synthesis of Cu-Fe LDHs/Bi2WO6 composite with ethylene glycol as reductant created the multivalent coexistence of the same metal element to achieve a self-circle redox reaction between metals. The photo-Fenton process by Cu-Fe LDHs/Bi2WO6 incredibly eliminated the limitation of strong acidic pH value applied in the Fenton process. ∙OH generated by Cu-Fe LDHs/Bi2WO6 was 5 times that of Cu-Fe LDHs during the photo-Fenton process. The complete degradation of RhB in the photo-Fenton process under the optimal conditions of initial pH= 6, 5 mmol/L of H2O2, and 1 g/L of Cu-Fe LDHs/Bi2WO6 dosage was far more than 46% of RhB degradation in the photocatalytic process and 76% of RhB degradation in the Fenton process. Cu-Fe LDHs/Bi2WO6 composite exhibited the excellent redox ability, electron transfer ability and reusability during the photo-Fenton process. The acceleration of Fe3+/Fe2+ cycles in the Cu-Fe LDHs/Bi2WO6/H2O2/Vis system was mainly ascribable to the combination of efficient transfer of photogenerated electrons and self-circle redox of Fe3+/Cu+. It is expected for the promising application of multivalent bimetallic photo-Fenton catalysts and rendering enlightenments for photo-Fenton catalytic oxidation reaction.