Oxytetracycline (OTC), a broad-spectrum antibiotic, has been extensively used as a food additive for livestock. Its extensive use has greatly increased the risk of chronic drug abuse and has also increased the risk of the resulting diseases. Therefore, in light of this emerging situation, the detection of OTC in both food and livestock is very important to reduce the risks and for diagnosis purposes . In this work, we have proposed an electrochemical aptasensor to quantify OTC. The biosensor shows considerable sensitivity and selectivity, and it can be easily operated and regenerated. Furthermore, for the first time, we have shown that an electrochemical aptasensor can be directly used to detect OTC in mouse blood serum and urine. This biosensor has the potential to aid in the analysis of residual OTC levels, as well as providing more pharmacokinetic information in the future.
While supercapacitors can deliver high electrical power, their low energy density limits their application. Here, we designed and fabricated a facile asymmetric supercapacitor (ASC) with excellent electrochemical performance, where MnO 2 nanoflowers (NFs) and La 2 O 3 nanospheres (NSs) were successfully electrodeposited onto carbon paper as work electrodes in an aqueous 0.5 M Na 2 SO 4 electrolyte. Such nanostructures endow the electrodes with short electrons, ion diffusion paths, and abundant charge adsorption sites. The assembled MnO 2 NF//La 2 O 3 NS asymmetric cell presents a gravimetric energy density of 80.56 Wh kg −1 , a volumetric energy density of 0.74 mWh cm −3 at 35.71 mA cm −3 , and excellent cycle performance. Moreover, a packaged device displays a superior energy density of 0.49 mWh cm −3 with a power density of 94.29 mW cm −3 . The satisfactory improvement in performance mainly stems from the homogeneous nanostructured architecture and an extended workable potential region of 0− 2.0 V. The resulting supercapacitors could have great potential for designing high energy and power density devices as effective power sources.
Crystalline iron oxides/hydroxides are generally preferred as supercapacitor electrode materials instead of the low-crystalline structure, despite the fact that an amorphous phase could have a comprehensive electrochemical performance owing to its structural disorder. Herein, we present a facile and scalable method for preparing amorphous FeOOH nanoflowers@multi-walled carbon nanotubes (FeOOH NFs@ MWCNTs) composites. The resulting hybrid nanoflowers hold a distinctive heterostructure composed of a self-assembled amorphous FeOOH nanofilm on the MWCNTs surface. The low-crystalline 1FeOOH NFs@1MWCNTs composites at pH 8 exhibit a high comprehensive capacitive performance, which may be attributed to the advantageous structural features. In a −0.85 to 0 V vs Ag/AgCl potential window, the prepared hybrid electrode delivers a high specific capacitance of 345 F g −1 at a current density of 1 A g −1 , good cycling stability (76.4% capacity retention over 5000 consecutive cycles), and outstanding rate performance (167 F g −1 at 11.4 A g −1 ). This work may trigger the possibilities of these nanomaterials for further application in supercapacitor electrodes, specifically low-crystalline oxide/ hydroxide-based electrode materials.
Lanthanum-based materials have attained increasing attention because of their high adsorption property of phosphate ions and their environmental harmlessness. However, challenges still remain to improve the phosphate adsorption capacity and find suitable materials for the lanthanum attachment substrate. Nickel foam with characteristics such as excellent uniformity, large specific surface area, high porosity, and low conductivity is considered to be the alternative for the preparation of lanthanum-based adsorption materials. An efficient adsorbent foamed nickel-based La (OH) 3 nanowire was first prepared with a facile one-step electrodeposition method. The batch static adsorption tests of simulative wastewater (e.g., coexisting ions and solution pH values) were employed to investigate the phosphate adsorption kinetics and solution matrix effects of the materials. The results indicate that the composite exhibits fast adsorption kinetics within 30 min and high selectivity to phosphate under interference from competing ions. The pH value of wastewater has great influence on the absorption of phosphate, and optimal adsorption capacity can be achieved over a pH 4−6 range. Various findings revealed that the adsorption behavior of lanthanum hydroxide/foamed nickel [La(OH) 3 /Ni] followed inner-sphere adsorption through the ligand-exchange mechanism. The prepared material is expected to be an enormous potential candidate for the removal of low-concentration phosphorus from effluents.
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