Simultaneous introduction of K⁺ and Rb⁺ into OMS-2 tunnels as an available strategy for substantially increasing the catalytic activity for benzene elimination

OMS-2 is one of the most promising catalysts for carcinogenic benzene elimination, and single-type alkali metals are typically introduced into the OMS-2 tunnels to modify its catalytic activity. Here, we reported a novel approach for significantly increasing the catalytic activity of OMS-2 via the simultaneous introduction of K⁺ and Rb⁺ into the tunnels. The catalytic results demonstrated that K⁺ and Rb⁺ codoped OMS-2 showed catalytic activity for benzene oxidation that exceeded those of K⁺ and Rb⁺ single-doped OMS-2, as evidenced by enormous decreases (△T₅₀ = 106 °C and △T₉₀ > 132 °C) in catalytic temperatures T₅₀ and T₉₀ (which correspond to benzene conversion percentages of 50% and 90%, respectively). The origin of the effect of K⁺ and Rb⁺ codoping on the catalytic activity of OMS-2 was experimentally and theoretically investigated via ¹⁸O₂ isotope labeling, CO temperature-programmed reduction, and density functional theory calculation. The higher catalytic activity of K⁺ and Rb⁺ codoped OMS-2 was attributed to its higher lattice oxygen activity as well as its higher oxygen vacancy defect concentrations compared to the single-doped OMS-2 cases.