Two-step pyrolytic engineering of carbon-doped Co3O4 with rich defects for efficient low-temperature CO oxidation

Abstract

A series of carbon-doped Co₃O₄ samples with rich defects are rationally synthesized by two-step pyrolysis of ZIF-67 in different atmospheres. Specifically, Co₃O₄/C-300 exhibits the lowest apparent activation energy (E_a = 47.6 kJ mol⁻¹) and the highest activity (T_100% = 120 °C) for CO oxidation, as well as excellent catalytic stability for 50 cycles. The intensive investigation of the structural and physicochemical properties of the catalysts demonstrates that the excellent catalytic performance is predominantly attributed to the synergistic effects of abundant active Co³⁺ sites, good low-temperature reducibility, more active oxygen species and better oxygen storage capacity (OSC). Besides, the in situ DRIFTS analysis reveals that CO is oxidized by O_ads on the surface active sites of the material to finally form CO₂. Thus, these findings may shed light on the design of carbon-doped metal oxides to approach reactions with superior performance by tuning the defect concentration of the material.