Catalytic oxidation of Hg⁰ with O₂ induced by synergistic coupling of CeO₂ and MoO₃

Based on Volcano plotting, the controlled combination of weak and strong bond strengths of a bimetallic catalyst has the potential to maximize the catalytic effect via the formation of intermediate bond strength between the reactant and the two different types of active sites. In this study, a rational design approach was adopted to couple MoO₃ and CeO₂ to maximize the catalytic oxidation of Hg⁰ using oxygen as the oxidizing agent. It is found that CeO₂ displayed a relatively strong bond strength with Hg⁰ while MoO₃ has relatively weak bond strength with Hg⁰; the pre-doping of MoO₃ results in the transformation of CeO₂ from clusters to the form with additional exposed CeO₂ (111) surface; the CeO₂ and MoO₃ show synergistic effect on the formation of Brønsted acid sites. Moreover, the results show that there is an overlap between the Hg⁰ desorption region of MoO₃ and the Hg⁰ adsorption region of CeO₂ (with adjusted optimum bond strength with Hg⁰), which contributes to the catalytic reaction of Hg⁰ by O₂. Therefore, this study reveals that the synergistic effects of the coupling of CeO₂ and MoO₃ induced the reaction between Hg⁰ and O₂, which is otherwise difficult.