Boosted toxicity reduction and deep removal of As(III) over porous Fe-doped Co3O4 nano brush-like array anode: Trade-off between electrocatalytic activity and adsorption capacity

Abstract

The development of transition metal oxide for the detoxification and removal of aqueous arsenite (As(III)) has long been relying on trial-and-error strategies due to lack of tuning principles. Herein, a boosted oxidation and adsorption by electrocatalysis strategy is proposed for toxicity reduction and deep removal of As(III). Porous Co₃O₄ nano-brush arrays decorated nickel foam (Co₃O₄ NBs/NF) has been designed as the model anode, and the electrocatalytic activity and adsorption capacity were regulated by the amount of Fe doping. A trade-off between electrocatalytic activity and adsorption capacity was discovered in the transition metal oxide. The experimental and density functional theory calculations verify that the electric field could simultaneously promote the catalytic oxidation and adsorption of As(III). The complete conversion of As(III) into As(V) and removing 1000 μg L¹ of total As in water to below 10 μg L¹ within 10 min were achieved by electrocatalytic oxidation and adsorption on the Fe-Co₃O₄ NBs/NF. The Fe-Co₃O₄ NBs/NF anode can work efficiently over a broad pH, mitigates the impact of competing anions, shows satisfactory structural stability and recyclability. This study provides a potent strategy to tune the electrocatalytic activity and adsorption capacity of transition metal oxide for efficient removal of As(III) in natural water.