Design of Co3O4/CeO2–Co3O4 hierarchical binary oxides for the catalytic oxidation of dibromomethane

Abstract Developing the catalysts that can efficiently degrade brominated volatile organic compounds (Br-VOCs) is a priority due to the low activity, the low product selectivity, and the low resistance to Br-poisoning. In this work, Co 3 O 4 /CeO 2 –Co 3 O 4 hierarchical binary oxides were designed as a high-performance catalyst for the catalytic oxidation of dibromomethane (CH 2 Br 2 ) as a model pollutant for Br-VOCs. The surface of carbon spheres was coated with a layer of CeO 2 nanoparticles, and core-shell CSs@CeO 2 were the precursors of Co 3 O 4 /CeO 2 –Co 3 O 4 hierarchical binary oxides. Co 3 O 4 /CeO 2 –Co 3 O 4 (HS) had a hierarchical porous structure, there was a strong interaction between Co 3 O 4 and CeO 2 ·Co 3 O 4 /CeO 2 –Co 3 O 4 (HS) showed an excellent catalytic activity, and its T 90 value was only 321 °C. Meanwhile, Co 3 O 4 /CeO 2 –Co 3 O 4 (HS) showed good stability for at least 30 h. Co 3 O 4 provided the active sites for CH 2 Br 2 oxidation, and the hierarchical porous structure and high specific surface area were conducive to the adsorption of CH 2 Br 2 molecules. Meanwhile, CeO 2 promoted the oxygen mobility of the composite and the oxidation performance of Co 3 O 4 . CH 2 Br 2 molecular firstly adsorbed on Co 3 O 4 /CeO 2 –Co 3 O 4 (HS) surface, and dissociated to form the intermediates (i.e., formate species, and methoxy species), which were finally oxidized to CO and CO 2 , and Br species were removed in the form of HBr and Br 2 .