Solution combustion derived oxygen vacancy-rich Co₃O₄ catalysts for catalytic formaldehyde oxidation at room...

Fabricating abundant oxygen vacancies is crucial for non-noble metal oxides to catalyze formaldehyde (HCHO) oxidation at room temperature. Here, a simple one-pot preparation method via solution combustion was found to produce oxygen vacancy-rich Co₃O₄ catalysts, avoiding delicate defect engineering. The catalyst was evaluated to result in 52% HCHO conversion in a dynamic flow reaction with ∼6 ppm HCHO, which was higher as compared to some other Co₃O₄ catalysts prepared in three methods of sol-gel, deposition precipitation and thermal decomposition. The optimal catalyst also exhibited high durability with steady HCHO conversion (∼47%) for more than 50 h. The catalyst characterizations revealed that the explosive solution combustion brought out two particular features of Co₃O₄, namely, the porous network structure with nano-holes and the abundant oxygen vacancies. The latter was demonstrated to increase the reactive oxygen species and to improve the reducibility and the oxygen transport capacity of Co₃O₄. The two features and the derived properties are beneficial to the activity and durability of Co₃O₄. The solution combustion method can serve as a simple and feasible way to fabricate abundant oxygen vacancies to provide room-temperature activity of Co₃O₄ for HCHO elimination at room temperature.