Boosting total oxidation of acetone over spinel MCoO (M = Co, Ni, Cu) hollow mesoporous spheres by cation-substituting effect.

Boosting total oxidation of volatile organic compounds (VOCs) over spinel CoO by cation-substituting effect is an effective solution, but the underlying mechanism has not yet been clearly elucidated. Herein, a series of spinel MCoO (M = Co, Ni, Cu) hollow mesoporous spheres (HMS) have been synthesized by solvothermal alcoholysis with goals to elaborate the cation-substituting effect on spinel CoO for total oxidation of VOCs. The physicochemical properties of spinel MCoO (M = Co, Ni, Cu) HMS have been well characterized and correlated with their catalytic activities. Results reveal that CuCoO HMS exhibited superior catalytic activity than those of NiCoO and CoCoO HMS for total oxidation of acetone and their catalytic activities followed the sequence of CuCoO > NiCoO > CoCoO. This phenomenon can be attributed to the cation-substituting effect, which resulted in the synthesized catalysts with different amounts of surface Co cations, active oxygen species, defective sites and reducible capabilities. Meanwhile, kinetics studies offer direct evidence to support that the cation-substituting effect played the decisive role in determining the catalytic activity, and the underlying mechanism has been proposed by correlating the structure-activity relationship. Moreover, CuCoO HMS also showed excellent long-term stability and good water tolerance due to its highly stable crystal phase and robust morphological structure, demonstrating its potential applications in the field of VOCs elimination.