Photolithographic Approaches for Fabricating Highly Ordered Nanopatterned Arrays

In this work, we report that large area metal nanowire and polymer nanotube arrays were successfully patterned by photolithographic approach using anodic aluminum oxide (AAO) templates. Nanowires were produced by electrochemical deposition, and nanotubes by solution-wetting. The highly ordered patterns of nanowire and nanotube arrays were observed using scanning electron microscopy (SEM) and found to stand free on the substrate. The method is expected to play an important role in the application of microdevices in the future

Synthesis and Growth Mechanism of Ni Nanotubes and Nanowires

Highly ordered Ni nanotube and nanowire arrays were fabricated via electrodeposition. The Ni microstructures and the process of the formation were investigated using conventional and high-resolution transmission electron microscope. Herein, we demonstrated the systematic fabrication of Ni nanotube and nanowire arrays and proposed an original growth mechanism. With the different deposition time, nanotubes or nanowires can be obtained. Tubular nanostructures can be obtained at short time, while nanowires take longer time to form. This formation mechanism is applicable to design and synthesize other metal nanostructures and even compound nanostuctures via template-based electrodeposition

A Novel CdS Quantum Dots Decorated 3D Bi2O2CO3 Hierarchical Nanoflower with Enhanced Photocatalytic Performance

Heterojunction engineering has shown great potential in the field of photocatalysis to deal with environmental pollutants. The design and synthesis of heterojunction photocatalysts with high efficiency and stability still face great challenges. In this work, a novel CdS quantum dots (QDs) decorated 3D Bi2O2CO3 hierarchical nanoflower heterojunction photocatalyst (Bi2O2CO3/CdS QDs) was synthesized to investigate the photocatalytic Rhodamine B (RhB) degradation performance. CdS QDs were evenly distributed on the surface of the Bi2O2CO3 nanoflower. Bi2O2CO3/CdS QDs showed significantly enhanced photocatalytic RhB degradation performance compared with pristine Bi2O2CO3 and CdS QDs. The enhanced photocatalytic performance was attributed to the synergistic effect of hierarchical structure and heterojunction, which greatly increased the active sites of the reaction and the photogenerated carriers transfer

Synthesis of network reduced graphene oxide in polystyrene matrix by a two-step reduction method for superior conductivity of the composite

Polymer/graphene composites have attracted much attention due to their unique organic-inorganic hybrid structure and exceptional properties. In this paper, we report the synthesis of polystyrene/reduced graphene oxide (PS/r-GO) composites by a two-step in situ reduction technique, which consists of a hydrazine hydrate reduction and a subsequent thermal reduction at 200 degrees C for 12 h. The structure and micromorphology of PS/r-GO composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. The results show that the GO can be efficiently reduced by the two-step in situ reduction method, and the r-GO sheets are well dispersed and ultimately form a continuous network structure in the polymer matrix. PS/r-GO composite films (5 wt% GO) are prepared by the hot press molding method, possessing a conductivity as high as 22.68 S m(-1). The superior conductivity arises from the high reduction degree of GO and its high dispersion and the formation of a network structure in the polymer matrix. These polymer/r-GO composites are expected to be applied in multiple electric devices. The techniques for preparing polymer/r-GO composite films could be further extended to other similar systems

Template-Free Synthesis of Mesoporous Hollow CuO Microspheres as Anode Materials for Li-Ion Batteries

We report the preparation and characterization of mesoporous hollow CuO (MPH-CuO) microspheres by thermal decomposition of hollow copper oxalate microspheres synthesized via the reaction of ammonium oxalate and copper chloride without using any template. The sample was characterized by Nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The electrochemical performance of MPH-CuO microspheres as anode materials in Li-ion batteries was evaluated. It was found that the MPH-CuO microspheres possessed an average diameter of 2.5 mu m, a pore size of 17.5 nnn, and a BET surface area of 15.2 m(2)/g. Their shells were composed of CuO nanocrystals with a size, of 17.9 nm. Compared with the dense CuO microspheres, the obtained MPH-CuO shows an enhanced electrochemical performance with a higher capacity of 599.4 mAh/g and a better cyclability (484 mAh/g after 15 cycles) because of its mesoporous hollow structure that provides quick intercalation and large accommodation of lithium ions together with short diffusion distance for lithium ions, suggesting a potential application in Li-ion batteries

Exploring Bayesian Optimization for Photocatalytic Reduction of CO₂

The optimization of photocatalysis is complex, as heterogenous catalysis makes its kinetic modeling or design of experiment (DOE) significantly more difficult than homogeneous reactions. On the other hand, Bayesian optimization (BO) has been found to be efficient in the optimization of many complex chemical problems but has rarely been studied in photocatalysis. In this paper, we developed a BO platform and applied it to the optimization of three photocatalytic CO2 reduction systems that have been kinetically modeled in previous studies. Three decision variables, namely, partial pressure of CO2, partial pressure of H2O, and reaction time, were used to optimize the reaction rate. We first compared BO with the traditional DOE methods in the Khalilzadeh and Tan systems and found that the optimized reaction rates predicted by BO were 0.7% and 11.0% higher, respectively, than the best results of optimization by DOE, and were significantly better than the original experimental data, which were 1.9% and 13.6% higher, respectively. In both systems, we also explored the best combination of the surrogate model and acquisition function for BO, and the results showed that the combination of Gaussian processes (GP) and upper confidence bound (UCB) had the most stable search performance. Furthermore, the Thompson system with time dependence was optimized with BO according to the selectivity of CH4. The results showed that the optimized reaction time of BO agreed with the actual experimental data with an error of less than 5%. These results suggest that BO is a more promising alternative to kinetic modeling or traditional DOE in the efficient optimization of photocatalytic reduction

RSC Adv.

Urchin-like ZnO microspheres were successfully prepared by thermal decomposition of hydrozincite synthesized via homogeneous precipitation of zinc nitrate and urea in the presence of a nonionic surfactant polyethylene glycol. The synthesis conditions, such as reaction temperature and time, precursor concentration, and the amount of surfactant added, as well as the catalytic properties of urchin-like ZnO microspheres as promoters for a commercial copper catalyst in dimethyldichlorosilane synthesis were investigated. In addition, the formation mechanism of urchin-like microspheres from hydrozincite to ZnO was proposed. The ZnO samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and N-2 adsorption. It was found that zinc nitrate concentration and the amount of surfactant are the key factors that lead to the formation of urchin-like ZnO microspheres. These ZnO samples had BET surface areas of 16-30 m(2) g(-1) and an average diameter of 3-8 mu m. Compared with commercial Zn microspheres and ZnO nanoparticles, urchin-like ZnO microspheres showed a better performance in dimethyldichlorosilane synthesis via the Rochow reaction due to their larger surface area, which created more interfacial contacts with the copper catalyst and active Cu3Si species. The work is helpful for developing novel catalyst promoters and understanding the role of the promoter in the Rochow reaction.Urchin-like ZnO microspheres were successfully prepared by thermal decomposition of hydrozincite synthesized via homogeneous precipitation of zinc nitrate and urea in the presence of a nonionic surfactant polyethylene glycol. The synthesis conditions, such as reaction temperature and time, precursor concentration, and the amount of surfactant added, as well as the catalytic properties of urchin-like ZnO microspheres as promoters for a commercial copper catalyst in dimethyldichlorosilane synthesis were investigated. In addition, the formation mechanism of urchin-like microspheres from hydrozincite to ZnO was proposed. The ZnO samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and N-2 adsorption. It was found that zinc nitrate concentration and the amount of surfactant are the key factors that lead to the formation of urchin-like ZnO microspheres. These ZnO samples had BET surface areas of 16-30 m(2) g(-1) and an average diameter of 3-8 mu m. Compared with commercial Zn microspheres and ZnO nanoparticles, urchin-like ZnO microspheres showed a better performance in dimethyldichlorosilane synthesis via the Rochow reaction due to their larger surface area, which created more interfacial contacts with the copper catalyst and active Cu3Si species. The work is helpful for developing novel catalyst promoters and understanding the role of the promoter in the Rochow reaction