Enhanced Catalytic Performance of Three-Dimensional Ordered Mesoporous Transition Metal (Co, Cu, Fe)-Doped CeO2 Catalysts for CO Catalytic Oxidation

Enhanced ·OH-Scavenging Activity of Cu-CeOx Nanozyme via Resurrecting Macrophage Nrf2 Transcriptional Activity Facilitates Diabetic Wound Healing

Diabetic wounds are a prevalent and devastating complication of diabetes, which may impede their healing and regeneration. In diabetic wounds, excess reactive oxygen species (ROS) activate the nuclear factor kappa-B pathway, leading to transcriptional silencing of nuclear factor erythroid 2-related factor 2 (Nrf2), resulting in a vicious cycle of oxidative stress and inflammation. Conventional nanozymes have limitations in preventing the continuous production of ROS, including the most oxidizing reactive hydroxyl radical (·OH), although they can remove pre-existing ROS. Herein, a novel antioxidant nanoplatform addresses this challenge by incorporating JSH-23 into the mesoporous of cupric-doped cerium oxide nanozymes. Additionally, for rapid wound adaptability and durable tissue adhesion, a nanozyme hydrogel spray consisting of oxidized sodium alginate and methacrylate gelatin is constructed, named OG@CCJs. This platform resurrects Nrf2 transcriptional activity of macrophages in vitro, curbing the production of ROS at its source, particularly ·OH, while enabling the nanozymes to scavenge previously generated ROS. OG@CCJs significantly alleviate oxidative stress in diabetic wounds in vivo, promoting wound healing. Overall, the proposed nanozyme-hydrogel spray with enhanced ·OH-scavenging activity uses a "two-track" antioxidant strategy to rebuild the antioxidant defense barrier of macrophages. This pioneering approach highlights the tremendous potential of OG@CCJs for facilitating diabetic wound healing.

Research on the elimination of low-concentration formaldehyde by Ag loaded onto Mn/CeO2 catalyst at room temperature

Formaldehyde (HCHO) is one of the major air pollutants, and its effective removal at room temperature has proven to be a great challenge. In this study, an Ag/Mn/CeO2 catalyst for the catalytic oxidation of low-concentration HCHO at room temperature was prepared by a hydrothermal-calcination method. The removal performance of the Ag/Mn/CeO2 catalyst for HCHO was systematically studied, and its surface chemical properties and microstructure were analyzed. The incorporation of Ag did not change the mesoporous structure of the Mn/CeO2 catalyst but reduced the pore size and specific surface area. The Ag species included metallic Ag as the main component and part of Ag+. The well-dispersed Ag species on the catalyst provided sufficient active sites for the catalytic oxidation of HCHO. The more the Ag active sites, the more the lattice defects and oxygen vacancies generated from the interaction of Ag with Mn/CeO2. Precisely because of this, the Ag/Mn/CeO2 catalyst exhibited high catalytic activity for HCHO at room temperature with a removal efficiency of 96.76% within 22 h, which is 22.91% higher than that of the Mn/CeO2 catalyst. Moreover, the Ag/Mn/CeO2 catalyst showed good cycling stability and the removal efficiency reached 85.77% after five cycles. Therefore, the as-prepared catalyst is an effective and sustainable material that can be used to remove HCHO from actual indoor polluted air. This paper provides ideas for the research and development of efficient catalysts.

Stabilization of reduced copper on ceria aerogels for CO oxidation

Photodeposition of Cu nanoparticles on ceria (CeO₂) aerogels generates a high surface area composite material with sufficient metallic Cu to exhibit an air-stable surface plasmon resonance. We show that balancing the surface area of the aerogel support with the Cu weight loading is a critical factor in retaining stable Cu⁰. At higher Cu weight loadings or with a lower support surface area, Cu aggregation is observed by scanning and transmission electron microscopy. Analysis of Cu/CeO₂ using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy finds a mixture of Cu²⁺, Cu⁺, and Cu⁰, with Cu⁺ at the surface. At 5 wt% Cu, Cu/CeO₂ aerogels exhibit high activity for heterogeneous CO oxidation catalysis at low temperatures (94% conversion of CO at 150 °C), substantially out-performing Cu/TiO₂ aerogel catalysts featuring the same weight loading of Cu on TiO₂ (20% conversion of CO at 150 °C). The present study demonstrates an extension of our previous concept of stabilizing catalytic Cu nanoparticles in low oxidation states on reducing, high surface area aerogel supports. Changing the reducing power of the support modulates the catalytic activity of mixed-valent Cu nanoparticles and metal oxide support.

Co/Cu-MFF derived mesoporous ternary metal oxide microcubes for enhancing the catalytic activity of the CO oxidation reaction

Metal–organic framework (MOF)-based derivatives with uniform micro/mesoporous structures have attracted a great deal of interest in various research fields. Herein, we report a simple strategy to design functional mesoporous ternary metal oxides with controlled composition through direct pyrolysis of Co/Cu bimetal-formate frameworks (Co/Cu-MFFs), which were prepared by a facile one-step liquid-phase precipitation method, exhibiting uniform distribution of two different metal species and good structural integrity. The obtained mesoporous ternary metal oxide Cu_xCo_3−xO₄ (x = 0.5, 1) microcubes exhibit much better performance for CO oxidation than pure Co₃O₄, which can be mainly attributed to their larger specific surface areas, stronger reducibility, and the synergistic effect of two active metal oxide components.

The fabricated Cu_xCo_3−xO₄ microcubes with structure and component merits exhibit good performance for CO oxidation.

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.

Hard-template synthesis of three-dimensional mesoporous Cu–Ce based catalysts with tunable architectures and their application in the CO catalytic oxidation

In this paper, 3D Cu–Ce-Ox catalysts with different pores were synthesized by controlling the calcination temperaturre. The CeCu20-600 showed the highest catalytic activity, where CO can be fully oxidized at 55 °C and expressed good stability.