Peili Liu

Fabrication of ZIF-8@SiO2 Micro/Nano Hierarchical Superhydrophobic Surface on AZ31 Magnesium Alloy with Impressive Corrosion Resistance and Abrasion Resistance

Superhydrophobic coatings are highly promising for protecting material surfaces and for wide applications. In this study, superhydrophobic composites, comprising a rhombic-dodecahedral zeolitic imidazolate framework (ZIF-8@SiO2), have been manufactured onto AZ31 magnesium alloy via chemical etching and dip-coating methods to enhance stability and corrosion resistance. Herein, we report on a simple strategy to modify hydrophobic hexadecyltrimethoxysilan (HDTMS) on ZIF-8@SiO2 to significantly improve the property of repelling water. We show that various liquids can be stable on its surface and maintain a contact angle higher than 150°. The morphologies and chemical composition were characterized by means of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FI-IR). In addition, the anticorrosion and antiattrition properties of the film were assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization and HT, respectively. Such a coating shows promising potential as a material for large-scale fabrication.

Rapid and efficient uranium(VI) capture by phytic acid/polyaniline/FeOOH composites

Uranium plays an indispensable role in nuclear energy, but there are limited land resources to meet the ever growing demand; therefore, a need exists to develop efficient materials for capturing uranium from water. Herein, we synthesize a promising adsorbent of phytic acid/polyaniline/FeOOH composites (PA/PANI/FeOOH) by oxidative polymerization. Phytic acid, acting asa gelator and dopant, plays an important role in the formation of polyaniline (PANI). The PA/PANI/FeOOH exhibites high adsorption capacity (qm=555.8mgg-1, T=298K), rapid adsorption rate (within 5min), excellent selectivity and cyclic stability. In addition, the results show that the adsorption isotherm is well fitted to the Langmuir isotherm model, and the adsorption kinetics agree with a pseudo-second order model. XPS analysis indicates that the removal of uranium is mainly attributed to abundant amine and imine groups on the surface of PA/PANI/FeOOH. Importantly, the removal of uranium from low concentrations of simulated seawater is highly efficient with a removal rate exceeding 92%. From our study, superior adsorption capacities, along with a low-cost, environmentally friendly and facile synthesis, reveal PA/PANI/FeOOH asa promising material for uranium capture.

Tube in tube ZnO/ZnCo2O4 nanostructure synthesized by facile single capillary electrospinning with enhanced ethanol gas-sensing properties

ZnO/ZnCo2O4 tube in tube nanostructures were successfully fabricated by single capillary electrospinning technology and calcination treatment. The tube in tube nanostructure was achieved via adjustment of the heating ratio during the calcination process. The composition and nanostructure of ZnO/ZnCo2O4 tube in tube were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission microscopy (HRTEM), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS). Excellent gas sensing performance of the structure was observed, with high response (58) of as-prepared material toward 100 ppm ethanol vapor at an optimal temperature of 150 °C. Rapid response time (5.6 s) and recovery time (4.8 s) were recorded at this optimal temperature. Noticeable response (13) was also observed of 100 ppm ethanol vapor at 75 °C. The tube in tube nanostructure, n–p heterojunction, and oxygen vacancies are potential reasons for the excellent gas sensing performance. The sensing mechanism of the as-prepared ZnO/ZnCo2O4 n–p heterostructure toward ethanol vapor was discussed.

Efficient removal of U(VI) from simulated seawater with hyperbranched polyethylenimine (HPEI) covalently modified SiO2 coated magnetic microspheres

Herein, we report on magnetic microspheres with numerous imine groups on the surface, which have great potential for U(VI) recovery in seawater. Hyperbranched polyethylenimine (HPEI) was covalently grafted onto the surface of the core–shell structured microspheres Fe3O4@SiO2. The microstructure and chemical composition of Fe3O4@SiO2-HPEI were comprehensively characterized. Consequently, the adsorption performance at low concentrations (3–30 μg L−1) under simulated seawater was investigated and the removal rate reached more than 90%. The superior performance of the Fe3O4@SiO2-HPEI is attributed to electrostatic force and chemical bonding (between amine/imine groups and U(VI)). We recommend, therefore, Fe3O4@SiO2-HPEI as a prospective alternative adsorbent in U(VI) recovery from seawater.

Hierarchical flower like double-layer superhydrophobic films fabricated on AZ31 for corrosion protection and self-cleaning

A stable double-layer superhydrophobic surface was successfully constructed on a magnesium alloy substrate by using a two-step immersion coating method to enhance corrosion resistance. The as-prepared surface had a static water contact angle measured as 160°. The microscopy and chemical composition analysis of the surface were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FI-IR), respectively. Importantly, the as-prepared superhydrophobic surface exhibited good stability and good corrosion resistance performance. In addition, the property of self-cleaning was investigated by using chalk powders. From our study, the superhydrophobic coatings could easily be applied to other materials.

In-situ anchoring of pyrrhotite on graphitic carbon nitride nanosheet for efficient immobilization of uranium

Enrichment of UVI is an urgent project for nuclear energy development. Herein, magnetic graphitic carbon nitride nanosheets were successfully prepared by in situ anchoring of pyrrhotite (Fe7 S8 ) on the graphitic carbon nitride nanosheet (CNNS), which were used for capturing UVI . The structural characterizations of Fe7 S8 /CNNS-1 indicated that the CNNS could prevent the aggregation of Fe7 S8 and the saturation magnetization was 4.69 emu g-1 , which meant that it was easy to separate the adsorbent from the solution. Adsorption experiments were performed to investigate the sorption properties. The results disclosed that the sorption data conformed to the Langmuir isotherm model with the maximum adsorption capacity of 572.78 mg g-1 at 298 K. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that the main adsorption mechanism are as follows: UVI is adsorbed on the surface of Fe7 S8 /CNNS-1 through surface complexation initially, then it was reduced to insoluble UIV . Thereby, this work provided an efficient and easy to handle sorbent material for extraction of UVI .