The supported Pt/CeO 2 catalysts are widely used for the catalytic oxidation of CO at ambient conditions. Herein, we reported a new strategy for modifying the interaction between Pt and CeO 2 support via pulsed steam treatment, which significantly optimized the catalytic performance of Pt/CeO 2 for CO oxidation. Specifically, the hollow CeO 2 nanospheres were prepared by using carbon spheres as sacrificial templates and then subjected to pulsed steam treatment at 150 °C for different times to obtain the CeO 2 -xH support (x means the time of pulsed steam treatment, min). It was found that the complete oxidation of CO can be achieved at 90 °C over the Pt/CeO 2 –50H sample, which was much lower than that (130 °C) on Pt/CeO 2 without pulsed steam treatment. The XPS and in-situ DRIFTS characterizations were conducted to reveal the high performance of the Pt/CeO 2 –50H catalyst for CO oxidation. It was found that the valence state of Pt significantly controlled by pulsed steam treatment was critical to the catalytic activity, whereby the presence of two types of active sites (Pt 0 -CO and Pt δ+ -CO) over Pt/CeO 2 –50H greatly promoted the combination of adsorbed CO and O 2 to generate CO 2 . Accordingly, this study provides a facile method to regulate the Pt valence state by pulsed steam treatment for CeO 2 support, which is critical to the CO oxidation activity.
Fabricating efficient and stable photocatalysts with an improved photocatalytic property is necessary to decontaminate wastewater. Herein, the Ce-MOF@h-CeO 2 microspheres with a hollow structure are designed and synthesized. The unique hollow structure with the π-π conjugate organic ligand offers abundant reactive sites and a charge transfer channel, both enhancing the performance of photocatalysts. The SEM and TEM tests showed that the Ce-MOF@h-CeO 2 composite retains the hollow microsphere structure, and its diameter is about 600–900 nm. At the same time, the prepared composite showed excellent photocatalytic performance for the degradation of rhodamine B (RhB) under visible-light-driven, within 30 min dark adsorption and 150 min visible light, the degradation rate for RhB reached 95.5% of Ce-MOF/h-CeO 2 -2 composite, which were 7.17 and 4.46 times of h-CeO 2 and Ce-MOF, respectively. Furthermore, the composite of Ce-MOF@h-CeO 2 -2 exhibited a remarkable photocatalytic hydrogen evolution efficiency (3419.38 μmol‧g −1 ‧h −1 ), which was 15.16 and 10.91 times greater than that of the pure samples. This study provides helpful results of the metal–organic framework that can sensitize effectively the inorganic semiconductor materials for improving photocatalytic performance.
Wound healing is a complex and sequential biological process that involves multiple stages. Although various nanomaterials are applied to accelerate the wound healing process, only a single stage is promoted during the process, lacking hierarchical stimulation. Herein, hollow CeO 2 nanoparticles (NPs) with rough surface and l -arginine inside ( Ah CeO 2 NPs) are developed as a compact and programmable nanosystem for sequentially promoting the hemostasis, inflammation, and proliferation stages. The rough surface of Ah CeO 2 NPs works as a nanobridge to rapidly closure the wounds, promoting the hemostasis stage. The hollow structure of Ah CeO 2 NPs enables the multireflection of light inside particles, significantly enhancing the light harvest efficiency and electron–hole pair abundance. Simultaneously, the porous shell of Ah CeO 2 NPs facilitates the electron–hole separation and reactive oxygen species production, preventing wound infection and promotion wound healing during the inflammation stage. The enzyme mimicking property of Ah CeO 2 NPs can alleviate the oxidative injury in the wound, and the released l -arginine can be converted into nitric oxide (NO) under the catalysis of inducible NO synthase, both of which promote the proliferation stage. A series of in vitro and in vitro biological assessments corroborate the effectiveness of Ah CeO 2 NPs in the wound healing process.
危险品化学品经营许可证（带存储）