Solid-State Construction of CuOx/Cu1.5Mn1.5O4 Nanocomposite with Abundant Surface CuOx Species and Oxygen Vacancies to Promote CO Oxidation Activity

Carbon monoxide (CO) oxidation performance heavily depends on the surface-active species and the oxygen vacancies of nanocomposites. Herein, the CuO_x/Cu_1.5Mn_1.5O₄ were fabricated via solid-state strategy. It is manifested that the construction of CuO_x/Cu_1.5Mn_1.5O₄ nanocomposite can produce abundant surface CuO_x species and a number of oxygen vacancies, resulting in substantially enhanced CO oxidation activity. The CO is completely converted to carbon dioxide (CO₂) at 75 °C when CuO_x/Cu_1.5Mn_1.5O₄ nanocomposites were involved, which is higher than individual CuO_x, MnO_x, and Cu_1.5Mn_1.5O₄. Density function theory (DFT) calculations suggest that CO and O₂ are adsorbed on CuO_x/Cu_1.5Mn_1.5O₄ surface with relatively optimal adsorption energy, which is more beneficial for CO oxidation activity. This work presents an effective way to prepare heterogeneous metal oxides with promising application in catalysis.

Ultra-fine platinum species supported on niobium pentoxide for CO oxidation

Platinum oxide supported on a Lewis acid niobium oxide (Nb₂O₅) support has been used for various heterogeneous and homogeneous catalysts. In this work, we used urea as a precipitating agent to obtain crystallized Nb₂O₅ with high surface area via a hydrothermal route. Nb₂O₅-supported Pt catalysts were subsequently synthesized via an incipient wetness impregnation approach. Multiple characterizations including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and nitrogen adsorption/desorption confirmed the identical structural and textural properties of the Nb₂O₅ support before and after the impregnation process. Furthermore, the X-ray absorption fine structure technique (XAFS) results with related data analysis indicate that the platinum species in the fresh and H₂-pretreated samples were in the form of single atoms or ultrafine clusters. In addition, the decrease in coordination number (CN) of the first-shell Pt–O bond, as well as the formation of Pt–Pt contribution with very low CN, after H₂-pretreatment was verified, which corresponds to the decrease of oxidation state for Pt species on the surface of supports. Thus, the ultrafine-clustered metallic Pt species are considered to be more active than the oxidized Pt single ions. The current results will be of great significance in controllable synthesis of active Pt-based catalysts for other catalytic oxidation reactions.

Ultrafine-clustered metallic Pt species are considered to be more active than oxidized Pt single ions for CO oxidation reaction.

Synthesis of a ceria-supported iron–ruthenium oxide catalyst and its structural transformation from subnanometer clusters to single atoms during the Fischer–Tropsch synthesis reaction

The transformation from subnanometer clusters to single atoms during Fischer–Tropsch synthesis was revealed by X-ray absorption fine structure analysis of a ceria-supported iron–ruthenium oxide catalyst.

Catalytically active ceria-supported cobalt–manganese oxide nanocatalysts for oxidation of carbon monoxide

The crystallinity of the surface of the two-dimensional Co₃O₄ phase governs the catalytic performance of ceria-supported cobalt–manganese oxide nanostructures.