Tuning the K+ Concentration in the Tunnel of OMS-2 Nanorods Leads to a Significant Enhancement of the Catalytic Activity for Benzene Oxidation

OMS-2 nanorods with tunable K+ concentration were prepared by a facile hydrothermal redox reaction of MnSO4, (NH4)(2)S2O8, and (NH4)(2)SO4 at 120 degrees C by adding KNO3 at different KNO3/MnSO4 molar ratios. The OMS-2 nanorod catalysts are characterized by X-ray diffraction, transmission electron microscopy, N-2 adsorption and desorption, inductively coupled plasma, and X-ray photoelectron spectrometry. The effect of K+ concentration on the lattice oxygen activity of OMS-2 is theoretically and experimentally studied by density functional theory calculations and CO temperature-programmed reduction. The results show that increasing the K+ concentration leads to a considerable enhancement of the lattice oxygen activity in OMS-2 nanorods. An enormous decrease (Delta T-50 = 89 degrees C; Delta T-90 > 160 degrees C) in reaction temperatures T-50 and T-90 (corresponding to 50 and 90% benzene conversion, respectively) for benzene oxidation has been achieved by increasing the K+ concentration in the K+-doped OMS-2 nanorods due to the considerable enhancement of the lattice oxygen activity.