Unveiling the Promoting Mechanism of H₂ Activation on CuFeO_x Catalyst for Low-Temperature CO Oxidation

The effect of H₂ activation on the performance of CuFeO_x catalyst for low-temperature CO oxidation was investigated. The characterizations of XRD, XPS, H₂-TPR, O₂-TPD, and in situ DRIFTS were employed to establish the relationship between physicochemical property and catalytic activity. The results showed that the CuFeO_x catalyst activated with H₂ at 100 °C displayed higher performance, which achieved 99.6% CO conversion at 175 °C. In addition, the H₂ activation promoted the generation of Fe²⁺ species, and more oxygen vacancy could be formation with higher concentration of O_α species, which improved the migration rate of oxygen species in the reaction process. Furthermore, the reducibility of the catalyst was enhanced significantly, which increased the low-temperature activity. Moreover, the in situ DRIFTS experiments revealed that the reaction pathway of CO oxidation followed MvK mechanism at low temperature (<175 °C), and both MvK and L-H mechanism was involved at high temperature. The Cu⁺-CO and carbonate species were the main reactive intermediates, and the H₂ activation increased the concentration of Cu⁺ species and accelerated the decomposition carbonate species, thus improving the catalytic performance effectively.