visible light

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  • 文章类型: Journal Article
    通过光催化氧化工艺从废水中去除药物被认为是一种有吸引力的方法和环境友好的解决方案。本报告旨在评估Ag/g-C3N4/ZnO纳米棒在制药行业废水处理中的实际应用潜力。催化剂是通过直接和环境友好的策略合成的。具体来说,通过简单的自组装方法构建了g-C3N4/ZnO纳米棒异质结构,然后通过光还原途径将Ag纳米颗粒修饰在g-C3N4/ZnO纳米棒上。结果表明,三种商业药物(扑热息痛,阿莫西林,在小剂量Ag/g-C3N4/ZnO纳米棒(0.08gL-1)的存在下,高浓度(40mgL-1)的头孢氨苄)被显着降解。Ag/g-C3N4/ZnO纳米棒光催化剂对扑热息痛的降解性能比原始g-C3N4、ZnO纳米棒高3.8、1.8、1.3倍,和g-C3N4/ZnO纳米棒。此外,Ag/g-C3N4/ZnO纳米棒具有出色的可重用性和化学稳定性,可实现78%的对乙酰氨基酚降解效率,并在五个循环后保持光催化剂的化学结构。此外,本研究还讨论了光催化机理的解释和光催化药物降解能力的比较。
    Pharmaceutical drugs\' removal from wastewater by photocatalytic oxidation process is considered as an attractive approach and environmentally friendly solution. This report aims to appraise the practical application potential of Ag/g-C3N4/ZnO nanorods toward the wastewater treatment of the pharmaceutical industry. The catalysts are synthesized by straightforward and environmentally-friendly strategies. Specifically, g-C3N4/ZnO nanorods heterostructure is constructed by a simple self-assembly method, and then Ag nanoparticles are decorated on g-C3N4/ZnO nanorods by a photoreduction route. The results show that three commercial drugs (paracetamol, amoxicillin, and cefalexin) with high concentration (40 mg L-1) are significantly degraded in the existence of a small dosage of Ag/g-C3N4/ZnO nanorods (0.08 g L-1). The Ag/g-C3N4/ZnO nanorods photocatalyst exhibits degradation performance of paracetamol higher 3.8, 1.8, 1.3 times than pristine g-C3N4, ZnO nanorods, and g-C3N4/ZnO nanorods. Furthermore, Ag/g-C3N4/ZnO nanorods have an excellent reusability and a chemical stability that achieved paracetamol degradation efficiency of 78% and remained chemical structure of the photocatalyst after five cycles. In addition, the photocatalytic mechanism explanation and comparison of photocatalytic drugs\' degradation ability have also been discussed in this study.
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  • 文章类型: Journal Article
    We have developed photochromic probes for the nicotinic acetylcholine receptor that exploit the unique chemical properties of the tetrafluoroazobenzene (4FAB) scaffold. Ultraviolet light switching and rapid thermal relaxation of the metastable cis configuration are the main drawbacks associated with standard AB-based switches. We designed our photoprobes to take advantage of the excellent thermodynamic stability of the cis-4FAB configuration (thermal half-life > 12 days at 37 °C in physiological buffer) and cis-trans photostationary states above 84%. Furthermore, the well-separated n-π* absorption bands of trans- and cis-4FAB allow facile photoswitching with visible light in two optical channels. A convergent 11-step synthetic approach allowed the installation of a trimethylammonium (TA) head onto the 4FAB scaffold, by means of an alkyl spacer, to afford a free diffusible 4FABTA probe. TAs are known to agonize nicotinic receptors, so 4FABTA was tested on mouse brain slices and enabled reversible receptor activation with cycles of violet and green light. Due to the very long-lived metastable cis configuration, 4FAB in vivo use could be of great promise for long term biological studies. Further chemical functionalization of this 4FAB probe with a maleimide functionality allowed clean cross-linking with glutathione. However, attempts to conjugate with a cysteine on a genetically modified nicotinic acetylcholine receptor did not afford the expected light-responsive channel. Our data indicate that the 4FAB photoswitch can be derivatized bifunctionally for genetically-targeted photopharmacology whilst preserving all the favorable photophysical properties of the parent 4FAB scaffold, however, the tetrafluoro motif can significantly perturb pharmacophore-protein interactions. In contrast, we found that the freely diffusible 4FABTA probe could be pre-set with green light into an OFF state that was biologically inert, irradiation with violet light effectively \"uncaged\" agonist activity, but in a photoreversible manner. Since the neurotransmitter acetylcholine has fully saturated heteroatom valences, our photoswitchable 4FABTA probe could be useful for physiological studies of this neurotransmitter.
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  • 文章类型: Journal Article
    M-doped NH2-MIL-125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) analyses, N2-sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible-light irradiations showed that the noble metal-doping on NH2-MIL-125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2-MIL-125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt- and Au-loaded NH2-MIL-125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH2-MIL-125(Ti), Pt/NH2-MIL-125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2-MIL-125(Ti).The photocatalytic mechanisms over M/NH2-MIL-125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2-MIL-125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2-MIL-125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal-doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions.
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