No abstract

This study evaluated the acute toxicity and biokinetics of intravenously administered silver nanoparticles (AgNPs) in mice. Mice were exposed to different dosages of AgNPs (7.5, 30 or 120 mg kg(-1) ). Toxic effects were assessed via general behavior, serum biochemical parameters and histopathological observation of the mice. Biokinetics and tissue distribution of AgNPs were evaluated at a dose of 120 mg kg(-1) in both male and female mice. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine silver concentrations in blood and tissue samples collected at predetermined time intervals. After 2 weeks, AgNPs exerted no obvious acute toxicity in the mice. However, inflammatory reactions in lung and liver cells were induced in mice treated at the 120 mg kg(-1) dose level. The highest silver levels were observed in the spleen, followed by liver, lungs and kidneys. The elimination half-lives and clearance of AgNPs were 15.6 h and 1.0 ml h(-1) g(-1) for male mice and 29.9 h and 0.8 ml h(-1) g(-1) for female mice. These results indicated that AgNPs could be distributed extensively to various tissues in the body, but primarily in the spleen and liver. Furthermore, there appears to be gender-related differences in the biokinetic profiles in blood and distribution in lungs and kidneys following an intravenous injection of AgNPs. The data from this study provides information on toxicity and biodistribution of AgNPs following intravenous administration in mice, which represents the worst case scenario of toxicity among all the different administration routes, and may shed light in the future use of products containing AgNPs in humans.

Electrochemical synthesis of urea provides a sustainable strategy that can be easily incorporated into currently distributed renewable energy systems. The main challenge that hindered the advancement of this technique lies in developing advanced electrocatalytic processes to utilize abundant and low-cost inorganic carbon and nitrogen sources for highly productive urea generation. Herein, we report an electrocatalytic reaction that converts carbon dioxide (CO 2 ) and nitric oxide (NO) into urea, with water as the hydrogen source, under ambient conditions. The yield rate and Faradaic efficiency of urea reach 15.13 mmol g −1 h −1 and 11.26% at a current density of 40 mA cm −2 under optimized conditions. The critical intermediates of *CO and *NH 2 for urea generation are obtained via the co-reduction of CO 2 and NO and then continuously interconnect to form the C−N bond. A preliminary techno-economic study is performed to discuss the practical application potential of this strategy for urea production.

Photocatalysis, which converts natural solar energy into chemical energy, has emerged as one of the most appealing technologies in the past decades. However, photocatalytic performances are limited by the poor absorption of visible light, charge‐carrier recombination during migration, and a high energy barrier for activating reactants. Oxygen vacancies in semiconductive metal oxides are reported to be vital to improve their photocatalytic efficiency. In this regard, this review provides a concise overview of oxygen vacancies in transition metal oxides in photocatalytic systems, including their functions, construction strategies, characterization methods, and applications. Moreover, an outlook on the current challenges and promising opportunities in this field is provided.

Urea electrosynthesis provides an intriguing strategy to improve upon the conventional urea manufacturing technique, which is associated with high energy requirements and environmental pollution. However, the electrochemical coupling of NO 3 − and CO 2 in H 2 O to prepare urea under ambient conditions is still a major challenge. Herein, self-supported core−shell Cu@Zn nanowires are constructed through an electroreduction method and exhibit superior performance toward urea electrosynthesis via CO 2 and NO 3 − contaminants as feedstocks. Both 1 H NMR spectra and liquid chromatography identify urea production. The optimized urea yield rate and Faradaic efficiency over Cu@Zn can reach 7.29 μmol cm −2 h −1 and 9.28% at −1.02 V vs RHE, respectively. The reaction pathway is revealed based on the intermediates detected through in situ attenuated total reflection Fourier transform infrared spectroscopy and online differential electrochemical mass spectrometry. The combined results of theoretical calculations and experiments prove that the electron transfer from the Zn shell to the Cu core can not only facilitate the formation of *CO and *NH 2 intermediates but also promote the coupling of these intermediates to form C−N bonds, leading to a high faradaic efficiency and yield of the urea product.