Boosting total oxidation of acetone over spinel MCo2O4 (M = Co, Ni, Cu) hollow mesoporous spheres by cation-substituting effect

Abstract

Boosting total oxidation of volatile organic compounds (VOCs) over spinel Co3O4 by cation-substituting effect is an effective solution, but the underlying mechanism has not yet been clearly elucidated. Herein, a series of spinel MCo2O4 (M = Co, Ni, Cu) hollow mesoporous spheres (HMS) have been synthesized by solvothermal alcoholysis with goals to elaborate the cation-substituting effect on spinel Co3O4 for total oxidation of VOCs. The physicochemical properties of spinel MCo2O4 (M = Co, Ni, Cu) HMS have been well characterized and correlated with their catalytic activities. Results reveal that CuCo2O4 HMS exhibited superior catalytic activity than those of NiCo2O4 and CoCo2O4 HMS for total oxidation of acetone and their catalytic activities followed the sequence of CuCo2O4 > NiCo2O4 > CoCo2O4. This phenomenon can be attributed to the cation-substituting effect, which resulted in the synthesized catalysts with different amounts of surface Co3+ 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, CuCo2O4 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.