A series of CuO-based catalysts supported on the α-MnO₂ nanowire were facilely synthesized and employed as the CO oxidation catalysts. The achieved catalysts were systematically characterized by XRD, SEM, EDS-mapping, XPS and H₂-TPR. The catalytic performances toward CO oxidation had been carefully evaluated over these CuO-based catalysts. The effects of different loading methods, calcination temperatures and CuO loading on the low temperature catalytic activity of the catalyst were investigated and compared with the traditional commercial MnO₂ catalyst with a block structure. It was found that the slenderness ratio of a CuO/α-MnO₂ nanowire catalyst decreases with the increase in CuO loading capacity. The results showed that when CuO loading was 3 wt%, calcination temperature was 200 °C and the catalyst that was supported by the deposition precipitation method had the highest catalytic activity. Besides, the α-MnO₂ nanowire-supported catalysts with excellent redox properties displayed much better catalytic performances than the commercial MnO₂-supported catalyst. In conclusion, the CuO-based catalysts that are supported by α-MnO₂ nanowires are considered as a series of promising CO oxidation catalysts.

In this work, a series of Cu₂O/S (S = α-MnO₂, CeO₂, ZSM-5, and Fe₂O₃) supported catalysts with a Cu₂O loading amount of 15% were prepared by the facile liquid-phase reduction deposition–precipitation strategy and investigated as CO oxidation catalysts. It was found that the Cu₂O/α-MnO₂ catalyst exhibits the best catalytic activity for CO oxidation. Additionally, a series of Cu₂O-CuO/α-MnO₂ heterojunctions with varied proportion of Cu⁺/Cu²⁺ were synthesized by further calcining the pristine Cu₂O/α-MnO₂ catalyst. The ratio of the Cu⁺/Cu²⁺ could be facilely regulated by controlling the calcination temperature. It is worth noting that the Cu₂O-CuO/α-MnO₂-260 catalyst displays the best catalytic performance. Moreover, the kinetic studies manifest that the apparent activation energy could be greatly reduced owing to the excellent redox property and the Cu₂O-CuO interface effect. Therefore, the Cu₂O-CuO heterojunction catalysts supported on α-MnO₂ nanotubes are believed to be the potential catalyst candidates for CO oxidation with advanced performance.

Magnetic polymers are often used as loading materials for ionic liquids because of their excellent magnetic separation properties. In this study, a novel imidazolium-based ionic liquid-modified magnetic polymer was synthesized by suspension polymerization and grafting, denoted as γ-Fe₂O₃@GMA@IM, and this magnetic polymer was used for the adsorption of the acid dye FCF. The magnetic polymer was characterized by SEM, FTIR, XRD, VSM and TGA. These techniques were used to reveal the overall physical properties of magnetic polymers, including the presence of morphology, functional groups, crystalline properties, magnetism and thermal stability. Studies have shown that γ-Fe₂O₃@GMA@IM can adsorb FCF in a wide pH range (2–10), with a maximum adsorption capacity of 445 mg/g. The adsorption data were more in line with the pseudo-second-order kinetic model and the Freundlich isotherm. In order to investigate its reusability, this study used 10% NaCl as the desorption solution, and carried out five batches of adsorption–desorption cycles. After five cycles, the adsorption effect was maintained at 98.3%, which showed a good recycling performance.