Unraveling the decisive role of surface CeO2 nanoparticles in the Pt-CeO2/MnO2 hetero-catalysts for boosting toluene oxidation: Synergistic effect of surface decorated and intrinsic O-vacancies

摘要

Oxygen vacancy engineering has been verified as an important approach to achieve the efficient degradation of VOCs in nanomaterials. Herein, a synthetic strategy of Pt-CeO2/MnO2 hetero-catalysts is developed to fine-manipulate the surface oxygen vacancies and catalytic activities through surface CeO2 decoration as a surface O-vacancy donor. Among these Pt-based catalysts, the optimal Pt-0.15Ce-Mn catalyst exhibits the greatest catalytic activity for toluene oxidation (T-99 = 155 degrees C), which is attributed to more oxygen vacancies, outstanding redox ability and well dispersion of Pt. Combined with experiments and DFT calculations, it has been demonstrated that the special role of introducing CeO2 NPs is to induce the generation of more O-vacancies, new structure defects (Mn3+ and Ce3+ species), and the lower formation energy of oxygen vacancy. Furthermore, the synergistic effect of dual O-vacancies (surface decorated and intrinsic O-vacancies) via an oxygen replenishment-migration pathway is the key to boost the remarkable catalytic activity for deep toluene oxidation. Finally, in situ DRIFTS reveals that partial toluene molecules can be adsorbed directly on surface adsorbed oxygen species replenished by gas-phase oxygen, and these catalysts with richer O-vacancies can effectively reduce the accumulation of by-product (phenolate, C6H5-OH).

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