Enhanced oxygen activation over self-supporting Cu2+ doped Co3O4 nanoneedle arrays for efficient HCHO oxidation at room temperature

Oxidation of indoor formaldehyde (HCHO) with catalysts at room temperature without energy input is a promising air-purification strategy. Herein, Cu2+ doped Co3O4 nanoneedles (Cu0.03-Co3O4) were developed for this purpose. On account of Cu2+ dopant, compact and aligned Co3O4 nanoneedles turn into interlaced, resulting in many more exposed adsorptive active sites (Co3+) and oxygen vacancies, which fuels the activation of oxygen adsorbed on Co3O4 and provides sufficient reactive oxygen species (ROS) to oxidize HCHO molecules. In the static reactor test, the apparent kinetic constant (k) for the room-temperature degradation endowed by Cu0.03-Co3O4 (k = 0.132 min-1) was 9.5 times higher than pristine Co3O4 (k = 0.014 min-1). Exploring the differences in micro electrons in catalysts before and after Cu2+ doping with Co3O4 from the perspective of charge. XPS and DFT results revealed that Cu2+ can activate the inert electrons around Co3O4, which helps to bind adsorbed oxygen and water molecules at oxygen vacancies to generate ROS, so as to achieve the purpose of removing HCHO at room temperature.