Interfacial effects in CuO/Co3O4 heterostructures enhance benzene catalytic oxidation performance

Abstract

To elucidate the impact of interfacial effects, CuO/Co₃O₄ catalysts with nanosheet-like heterostructures were synthesized via a facile approach (i.e. precursor calcination) and utilized for benzene catalytic oxidation. The results indicated that under a high space velocity of 60 000 mL g⁻¹ h⁻¹, the heterostructural CuO/Co₃O₄ catalyst can effectively oxidize benzene at a relatively low temperature of 250 °C, much lower than that of each component. The CuO/Co₃O₄ catalyst also exhibited excellent recyclability and high stability over 10 continuous cycles and a 100 h long time-on-stream test. Additionally, the remarkable benzene oxidation capability/stability of CuO/Co₃O₄ was further validated by experiments in the presence of water vapour and CO₂, in which no detrimental impacts were shown. A combination of characterization techniques indicated that the outstanding catalytic performance, coupled with improved low-temperature reducibility and enhanced reactant adsorption capacity, was attributed to the interfacial effects in the CuO/Co₃O₄ catalyst. Furthermore, in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) experiments demonstrated that phenol and carbonate species were the main intermediates formed during the benzene oxidation process. Density functional theory (DFT) calculations demonstrated that the superior catalytic performance of CuO/Co₃O₄ was attributed to the favourable benzene adsorption energy (i.e. beneficial for the bond cleavage of benzene), consistent with the experimental and kinetic activation energy results. It is anticipated that utilization of the interfacial effects in the heterostructural metal oxides is an efficient and low-cost way for developing various highly effective catalysts.