Unveiling the water-resistant mechanism of Cu(I)-O-Co interfaces for catalytic oxidation

Abstract

The development of low-temperature and water-resistant heterogeneous catalysts without noble metals is vital in the effective treatment of atmospheric pollutants in practical application. Herein, we report that Cu(I)-O-Co interfaces of ultrafine CuOx on Co3O4 prepared by co-precipitation exhibit promising low-temperature activity and good water resistance. Experiment results together with density functional theory (DFT) calculations not only verify that Cu+ species are stabilized over Cu(I)-O-Co interfaces because of the strong interaction between Cu2O1 and Co3O4, but also demonstrate that the Cu(I)-O-Co interface facilitates oxygen species activation for promoting catalytic oxidation and reduces the accumulation of hydroxyl and bicarbonate species on the surface of CuOx/Co3O4. DFT calculations also reveal that the CO oxidation rate-limiting step via the dissociation pathway under dry conditions is the Co-OO-Cu species dissociation while the CO coupling with the adsorbed O2 becomes the rate determining step for CO oxidation through the direct pathway over Cu(I)-O-Co interface under humid conditions. Further, the CuOx/Co3O4 catalyst also exhibits superior and stable catalytic activity for toluene oxidation, comparable with partial supported noble metal catalysts (T90 = 190 °C). The present work gives a useful strategy for the rational design of low-temperature and water-resistant non-precious-based catalysts to be applicable in CO and toluene removal in practical applications.