Sm2O3/Co3O4 catalysts prepared by dealloying for low-temperature CO oxidation

Synergistic formation of samarium oxide/graphene nanocomposite: A functional electrocatalyst for carbendazim detection

Herein, an electrochemical sensor based on samarium oxide anchored, reduced graphene oxide (Sm₂O₃/RGO) nanocomposite was developed for the rapid detection of carbendazim (CBZ). Different characterization methods were infused to deeply examine the morphology, composition, and elemental state of Sm₂O₃/RGO nanocomposite. The Sm₂O₃/RGO modified electrode exhibits an excellent electro-catalytic performance toward CBZ detection with a peak potential of +1.04 V in phosphate buffer solution (pH 3.0), which is superior to the RGO-, Sm₂O₃- and bare- electrodes. This remarkable activity can be credited to the synergetic effect generated by the robust interaction between Sm₂O₃ and RGO, resulting in a well-enhanced electrochemical sensing ability. Impressively, the fabricated sensor shows improved electrochemical performance in terms of the wide working range, detection limit, and strong sensitivity. On a peculiar note, the electrochemical sensing performances of CBZ detection based on Sm₂O₃/RGO nanocomposite demonstrate an extraordinary behavior compared to the prior documented electro-catalyst. In addition, the fabricated Sm₂O₃/RGO sensor also displays good operational stability, reproducibility, and repeatability towards the detection of CBZ. Furthermore, it was successfully applied to the CBZ detection in food and environmental water samples with satisfactory recovery. In accordance with our research findings, the Sm₂O₃/RGO nanocomposite could be used as an electro-active material for effectual electrochemical sensing of food and environmental pollutants.

CO Oxidation over Metal Oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2) Doped CuO-Based Catalysts Supported on Mesoporous Ce0.8Zr0.2O2 with Intensified Low-Temperature Activity

CuO-based catalysts are usually used for CO oxidation owing to their low cost and excellent catalytic activities. In this study, a series of metal oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2)-doped CuO-based catalysts with mesoporous Ce0.8Zr0.2O2 support were simply prepared by the incipient impregnation method and used directly as catalysts for CO catalytic oxidation. These mesoporous catalysts were systematically characterized by X-ray powder diffraction (XRD), N2 physisorption, transmission electron microscopy (TEM), energy-dispersed spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS), and H2 temperature programmed reduction (H2-TPR). It was found that the CuO and the dopants were highly dispersed among the mesoporous framework via the incipient impregnation method, and the strong metal framework interaction had been formed. The effects of the types of the dopants and the loading amounts of the dopants on the low-temperature catalytic performances were carefully studied. It was concluded that doped transition metal oxides could regulate the oxygen mobility and reduction ability of catalysts, further improving the catalytic activity. It was also found that the high dispersion of rare earth metal oxides (PrO2, Sm2O3) was able to prevent the thermal sintering and aggregation of CuO-based catalysts during the process of calcination. In addition, their presence also evidently improved the reducibility and significantly reduced the particle size of the CuO active sites for CO oxidation. The results demonstrated that the 15CuO-3Fe2O3/M-Ce80Zr20 catalyst with 3 wt. % of Fe2O3 showed the best low-temperature catalytic activity toward CO oxidation. Overall, the present Fe2O3-doped CuO-based catalysts with mesoporous nanocrystalline Ce0.8Zr0.2O2 solid solution as support were considered a promising series of catalysts for low-temperature CO oxidation.

Rod-Like Nanoporous CeO2 Modified by PdO Nanoparticles for CO Oxidation and Methane Combustion with High Catalytic Activity and Water Resistance

A PdO/CeO2 composite with a rod-like nanoporous skeletal structure was prepared by combining the dealloying of Al-Ce-Pd alloy ribbons with calcination. For CO oxidation and CH4 combustion, the nanoporous PdO/CeO2 composite exhibits excellent catalytic activity, and the complete reaction temperatures of CO and CH4 are 80 °C and 380 °C, respectively. In addition, the composite possesses excellent cycle stability, CO2 toxicity, and water resistance, and the catalytic activity hardly decreases after 100 h of long-term stability testing in the presence of water vapour (2 × 105 ppm). The results of a series of characterizations indicate that the enhanced catalytic activity can be attributed to the good dispersion of the PdO nanoparticles, large specific surface area, strong redox capacity, interaction between PdO and CeO2, and more surface active oxygen on PdO. The results of the characterization and experiments also indicate that the PdO nanoparticles, prepared by combining dealloying and calcination, have a stronger catalytic activity than do Pd nanoparticles. Finally, a simple model is used to summarize the catalytic mechanism of the PdO/CeO2 composite. It is hoped that this work will provide insights into the development of high-activity catalysts.