Selective Electrocatalytic Reduction of Oxygen to Hydroxyl Radicals via 3-Electron Pathway with FeCo Alloy Encapsulated Carbon Aerogel for Fast and Complete Removing Pollutants.

We reported the selective electrochemical reduction of oxygen (O2 ) to hydroxyl radicals (. OH) via 3-electron pathway with FeCo alloy encapsulated by carbon aerogel (FeCoC). The graphite shell with exposed -COOH is conducive to the 2-electron reduction pathway for H2 O2 generation stepped by 1-electron reduction towards to . OH. The electrocatalytic activity can be regulated by tuning the local electronic environment of carbon shell with the electrons coming from the inner FeCo alloy. The new strategy of . OH generation from electrocatalytic reduction O2 overcomes the rate-limiting step over electron transfer initiated by reduction-/oxidation-state cycle in Fenton process. Fast and complete removal of ciprofloxacin was achieved within 5 min in this proposed system, the apparent rate constant (kobs ) was up to 1.44±0.04 min-1 , which is comparable with the state-of-the-art advanced oxidation processes. The degradation rate almost remains the same after 50 successive runs, suggesting the satisfactory stability for practical applications.