Catalytic oxidation of vinyl chloride over Co-Ce composite oxides derived from ZIF-67 template:Effect of cerium incorporation

Transition metal oxides are regarded as an economical and efficient catalytic alternate for catalytic oxidation of volatile organic compounds(VOCs)emissions.The morphological decoration and the incorporation of extrinsic metals were demonstrated to be effective strategies for achieving noticeable catalytic improvement.In this work,a novel Co-Ce composite oxides catalyst was obtained by the pyrolysis of ZIF-67 template with the impregnation of certain cerium cations(denoted as ZIF-CoCe).Compared with the reference Co-Ce composite oxides by the sol-gel(denoted as SG-CoCe)and physical mixing(denoted as MIX-CoCe)methods,ZIF-CoCe delivers significantly higher catalytic activity for vinyl chloride oxidation,which are demonstrated to be closely related with its superior redox capacity,more abundance of surface active Co^(3+)sites and adsorbed active oxygen species from oxygen vacancies.In addition,the unique cage-like morphological feature of the Co-based catalysts derived from ZIF-67 template plays a crucial function in kinetically facilitating the mass transfer of catalytic reaction and promoting the catalytic VC oxidation activity.With regard to in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)analysis,enol and carboxylic acid species are identified to be the key organic intermediates during catalytic vinyl chloride oxidation.

Synergistic regulation of dielectric-magnetic dual-loss and triple heterointerface polarization via magnetic MXene for high-performance electromagnetic wave absorption

The single dielectric/magnetic loss mechanism and invalid polarization loss are the crucial issues which limit the exploitation of multi-component electromagnetic wave(EMW)absorption materials,especially Ti_(3)C_(2)T_(x) MXene based absorption materials.In this work,a series of loosely packed accordion-like 3D NiCo/CeO_(2)/Ti_(3)C_(2)T_(x) with tunable and high-efficient EMW absorption were fabricated by introducing self-assembled NiCo alloys on the surface of Ti_(3)C_(2)T_(x) and subsequent anchoring of CeO_(2).On the one hand,the magnetic NiCo particles and highly conductive Ti_(3)C_(2)T_(x) achieved the dielectric-magnetic dual-loss.On the other hand,the triple interfacial polarization among NiCo/CeO_(2)/Ti_(3)C_(2)T_(x) further enhanced the relaxation loss.In addition,the effects of cerium ions on tuning the compositional structure,electromagnetic parameters and impedance behavior of the composites are explored.The NiCo/CeO_(2)/Ti_(3)C_(2)T_(x)-0.1 performed a wide absorption bandwidth of 6.32 GHz at 1.9 mm,as well as,the minimum reflection loss value of-42.48 dB at 2.0 mm.This work putted forward a new synergistic regulation strategy of dielectric-magnetic dual-loss and triple heterointerface polarization via magnetic MXene for high-performance EMW absorption,which may shed new light on the fabrication of multiple-component synergistic loss absorption materials.