A Review of Co₃O₄-based Catalysts for Formaldehyde Oxidation at Low Temperature: Effect Parameters and Reaction Mechanism

As a main pollutant in indoor environments, formaldehyde has high toxicity and a long release period. The use of catalytic-oxidation technique to remove formaldehyde can effectively improve indoor air quality. Spinel Co₃O₄ is an inexpensive catalyst with good low-temperature catalytic activity for formaldehyde oxidation. This paper systematically reviews the progress of research on Co₃O₄-based catalysts for formaldehyde oxidation in recent years. First, the limited performance of pristine Co₃O₄ and influencing factors (e.g., morphology, crystal face exposure, surface oxygen vacancy, surface reactive species, and environmental factors) is described. Subsequently, we introduce current modification methods to improve catalytic activity, including Co₃O₄/transition metal oxide composites, Co₃O₄-supported noble metals, and alkali-metal-ion doping. The reaction mechanism of catalytic oxidation for formaldehyde on Co₃O₄-based catalysts is also discussed. Finally, perspectives on challenges related to Co₃O₄ catalysts for formaldehyde oxidation are proposed.