Efficient SO₂ Removal and Highly Synergistic H₂O₂ Production Based on a Novel Dual-Function Photoelectrocatalytic System

The direct conversion of SO 2 to SO 3 is rather difficult for flue gas desulfurization due to its inert dynamic with high reaction activation energy, and the absorption by wet limestone-gypsum also needs the forced oxidation of O 2 to oxidize sulfite to sulfate, which is necessary for additional aeration. Here, we propose a method to remove SO 2 with highly synergistic H 2 O 2 production based on a novel dual-function photoelectrocatalytic (PEC) system in which the jointed spontaneous reaction of desulfurization and H 2 O 2 production was integrated instead of nonspontaneous reaction of O 2 to H 2 O 2 . SO 2 was absorbed by alkali liquor then oxidized quickly into SO 4 2– by a nanorod α-Fe 2 O 3 photoanode, which possessed high alkali corrosion resistance and electron transport properties. H 2 O 2 was produced simultaneously in the cathode chamber on a gas diffusion electrode and was remarkably boosted by the conversion reaction of SO 3 2– to SO 4 2– in the anode chamber in which the released chemical energy was effectively used to increase H 2 O 2 . The photocurrent density increased by 40% up to 1.2 mA·cm –2, and the H 2 O 2 evolution rate achieved 58.8 μmol·L –1 ·h –1 ·cm –2 with the synergistic treatment of SO 2, which is about five times than that without SO 2 . This proposed PEC cell system offers a cost-effective and environmental-benign approach for dual purpose of flue gas desulfurization and simultaneous high-valued H 2 O 2 production.