Kuo Jiang,Songbai Liu,Yu Luo,Qiang Li,Haiyang Wang
A polyglycol-assisted spreading deposition (PASD) method has been used to prepare the high-quality ZrO 2 thin film on single crystalline Si (111) substrate. The structure and composition of the films were studied by SEM, XRD and UV Raman techniques. Characterization results indicated that the ZrO 2 films were composed of nano-sized small particles and have a crack-free, dense and homogeneous microstructure. After a heat treatment of 10 min at 700–900 °C, the films showed a mixture of monoclinic and tetragonal ZrO 2 phases. And the grain sizes of monoclinic and tetragonal phases in the ZrO 2 films were 5–16 nm and 10–18 nm, respectively. In addition, the thin films of Y 2 O 3 -stabilized ZrO 2 (YSZ), La 2 Zr 2 O 7 , and the multilayer thin films of La 2 Zr 2 O 7 /YSZ were also fabricated by the PASD method.
Yanfu Ma,Guangyue Xu,Hao Wang,Yingxiong Wang,Ying Zhang,Yao Fu
In this study, rare earth (RE) metal doped ZrO2 was prepared by a surfactant-assisted coprecipitation/hydrothermal crystallization method and used to load Co as catalyst for the hydrogenation of aromatic carbonyl compounds in water. Furfural was hydrogenated to furfural alcohol in water with up to 95 mol % yield over Co/ZrLa0.2Ox at 40 °C, 2 MPa H2 in 10 h. The doping of rare earth metal oxide has three advantages: (I) it promotes the ZrO2 to reach a small-sized, stable, and high-activity tetragonal phase zirconia and thus lead to a high specific surface area for metal loading; (II) it interacts with Co to reach an ultrasmall average particle size of 1.1 nm; and (III) it modifies the ZrO2 surface to increase the amount of acidic sites for the adsorption of carbonyl feedstock. The adsorption experiment indicated a tight interaction between not only the carrier and C═O bond but also the Co clusters and C═O bond, which were of benefit for the hydrogenation of carbonyl groups. The surfactant addition during the carrier preparation improves the strong metal–support interactions (SMSI) to promote Co dispersion and stability. Various rare earth metals including La, Pr, Nd, and Ce could modify ZrO2 with a similar mechanism. The as-prepared Co catalyst could also catalyze the selective hydrogenation of various aromatic aldehydes and ketones (such as 5-hydroxymethyl furfural, benzaldehyde, and acetophenone) in water, and 100% yield to corresponding alcohols was achieved. The catalyst remained stable and showed little deactivation during the recycling tests. This study not only presented a high-efficient, low-cost, and stable catalyst for the selective hydrogenation of various aromatic aldehydes and ketones but also give rise to an understanding of rare earth metal oxide doped ZrO2 supported nano Co ternary catalysts.
Jie Meng,Peng Zhang,Qingjie Liu,Pan Ran,Shuang Xie,Junwu Wei,Xiaohong Li
Antibacterial electrotherapy is currently activated by external electric field or self-powered generators, but usually needs complicated power management circuits. Herein, near-infrared illumination (NIR) of pyroelectric nanoparticles (NPs) produces a built-in electric field to address the effectiveness and safety concerns in the antibacterial treatment. Janus tBT@PDA NPs were obtained by capping polydopamine (PDA) on tetragonal BaTiO 3 (tBT) NPs through defining the polymerization time, followed by ciprofloxacin (CIP) loading on the PDA caps to fabricate Janus tBT@PDA-Cip NPs. NIR illumination of PDA caps creates temperature variations on tBT NPs to generate photothermal and pyroelectric effects. Finite element simulation reveals a pyroelectric potential of over 1 V and sufficient reactive oxygen species (ROS) are produced to exhibit pyroelectric dynamic therapy (PEDT). The elevated temperature on one side of the Janus NPs produces thermophoretic force to drive NP motion, which enhances interactions with bacteria and overcomes limitations in the short action distance and lifespan of ROS. The pyroelectric field accelerates CIP release through weakening the π-π stacking and electrostatic interaction with PDA and also interrupts membrane potentials of bacteria to enhance CIP invasion into bacteria. The synergistic antibacterial effect of pyroelectric tBT@PDA-Cip NPs causes the fully recovery of S. aureus -infected skin wounds and regeneration of intact epidermis, blood vessels and hair follicles, while no obvious pathological change or inflammatory lesion is detected in the major organs. Thus, the pyroelectric Janus nanomotors demonstrate synergistic PEDT/photothermal/antibiotic effects to enhance antibacterial efficacy while avoiding the necessity of excessive heat, ROS and antibiotic doses. Statement of significance Antibacterial treatment is challenged by antibiotics-derived side effects and the evolution of resistant strains. Phototherapy is commonly associated with excessive heat and oxidative stress , and their combinations with other agents are especially encouraged to strengthen antibacterial efficacy while alleviating the associated side effects. Electric field is another activator to generate antibacterial abilities, but usually requires complicated power management and bulk electrodes, making it inconvenient in a biological setup. To address these challenges, we propose a strategy to generate microelectric field on nanoparticles themselves and achieve synergistic electrodynamic-photothermal-antibiotic therapies. The pyroelectric effect weakens interactions between nanoparticles and antibiotics to accelerate drug release, and the built-in pyroelectric field increases membrane fluidity to enhance bacterial uptake of antibiotics.
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