Siyuan Xiang

Facile synthesis of manganese oxide loaded hollow silica particles and their application for methylene blue degradation

A facile poly acrylic acid (PAA) soft templating method was developed to fabricate manganese oxide loaded hollow silica particles (MHSPs). The synthesis involves PAA-Mn aggregation to form spherical particles and silica coating layer formation on the outer surface of the particles. Subsequent calcination in air at 500 °C removes the polymer inside the particles, and hollow silica spheres with trapped metal oxide particles are thus formed. The PAA traps the Mn ions and forms aggregates which template the silica shell formation in this process. The Mn content and the structure of the MHSPs can be tuned by changing doses of the Mn salt initially added. Moreover, decomposition of PAA during calcination endows high surface areas of the MHSPs. Catalytic oxidation of methylene blue (MB) with H2O2 was tested on the MHSPs. The results show that the MHSPs with hollow structure and high surface areas enhance the catalytic activity compare to the corresponding manganese oxide solid particles (MSPs). This strategy can also be used to synthesize other metal oxides (such as MgO and NiO) loaded hollow silica particles.

Facile fabrication of mesoporous N-doped Fe3O4@C nanospheres as superior anodes for Li-ion batteries

A facile method was developed for fabricating mesoporous N-doped carbon coated Fe3O4 (N-mFe3O4@C) nanospheres using arabic gum (AG) as carbon precursor. The N-mFe3O4@C nanospheres can deliver a reversible capacity of 1273 mA h g−1 after 200 cycles at 0.2 C and exhibit excellent rate capability of 596 mA h g−1 at 1 C and 441 mA h g−1at 2 C, respectively.

A facile two-step etching method to fabricate porous hollow silica particles.

We report here the fabrication of hollow silica particles with mesopores larger than 10nm on their wall via a facile two-step etching method. Different from the conventional template method, the new method uses the silica particles as starting materials, which were synthesized using the well-known Stöber method. In the hollow silica preparation, first, we gently etch the silica particles with a NaOH solution without using template molecules to make them porous. Then, we coat the porous silica particles with poly-dimethyldiallylammonium chloride (PDDA) and treat the PDDA-coated porous silica with an ammonia solution to form the hollow silica nanospheres. In this study, we found that the NaOH dosage and ammonia concentration have significant impact on the morphology of the final products. Adsorption was also studied and results show that the hollow nanospheres can effectively uptake protein-based biomolecules (hemoglobin).

Tunable Polymer Brush/Au NPs Hybrid Plasmonic Arrays Based on Host−guest Interaction

The fabrication of versatile gold nanoparticle (Au NP) arrays with tunable optical properties by a novel host-guest interaction are presented. The gold nanoparticles were incorporated into polymer brushes by host-guest interaction between β-cyclodextrin (β-CD) ligand of gold nanoparticles and dimethylamino group of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). The gold nanoparticle arrays were prepared through the template of PDMAEMA brush patterns which were fabricated combining colloidal lithography and surface-initiated atom-transfer radical polymerization (SI-ATRP). The structure parameters of gold nanoparticle patterns mediated by polymer brushes such as height, diameters, periods and distances, could be easily tuned by tailoring the etching time or size of colloidal spheres in the process of colloidal lithography. The change of optical properties induced by different gold nanoparticle structures was demonstrated. The direct utilization of PDMAEMA brushes as guest avoids a series of complicated modification process and the PDMAEMA brushes can be grafted on various substrates, which broaden its applications. The prepared gold naoparticle arrays are promising in applications of nanosensors, memory storage and surface enhanced spectroscopy.

Hierarchical-Multiplex DNA Patterns Mediated by Polymer Brush Nanocone Arrays That Possess Potential Application for Specific DNA Sensing

This paper provides a facile and cost-efficient method to prepare single-strand DNA (ssDNA) nanocone arrays and hierarchical DNA patterns that were mediated by poly(2-hydroxyethyl methacrylate) (PHEMA) brush. The PHEMA brush nanocone arrays with different morphology and period were fabricated via colloidal lithography. The hierarchical structure was prepared through the combination of colloidal lithography and traditional photolithography. The DNA patterns were easily achieved via grafting the amino group modified ssDNA onto the side chain of polymer brush, and the anchored DNA maintained their reactivity. The as-prepared ssDNA nanocone arrays can be applied for target DNA sensing with the detection limit reaching 1.65 nM. Besides, with the help of introducing microfluidic ideology, the hierarchical-multiplex DNA patterns on the same substrate could be easily achieved with each kind of pattern possessing one kind of ssDNA, which are promising surfaces for the preparation of rapid, visible, and multiplex DNA sensors.

Functional interface based on silicon artificial chamfer nanocylinder arrays (CNCAs) with underwater superoleophobicity and anisotropic properties

A functional interface based on silicon chamfer nanocylinder arrays (CNCAs) was successfully fabricated by carrying out secondary etching of silicon nanopillar arrays via a facile inclined etching method. The structure of the novel CNCAs was finely modulated by varying the nanopillar array structure and the etching conditions. The underwater oil wetting behavior of this CNCAs-based interface can be easily modulated from superoleophilic (oil contact angle (OCA) of ~8.13°) state to superoleophobic (OCA of ~163.79°) state by modifying the surface using different substances. Moreover, a reversible transformation of underwater oil wetting behavior from superoleophobic (OCA of ~155.67°) state to oleophilic (OCA of ~31.27°) state was achieved by grafting a temperature-responsive polymer onto this specific asymmetric structure. The functional interface exhibited isotropic wetting behavior under certain oleophilic conditions. Chemically heterogeneous structures, obtained via asymmetry modification of CNCAs, exhibited amphiphobic properties while maintaining their anisotropic wetting ability.

Large-scale Au nanoparticle cluster arrays with tunable particle numbers evolved from colloidal lithography

The assembly of metal nanoparticles (NPs) can regulate their plasmon resonance properties to pursue the best properties for applications. However, the controllable assembly of large-scale metal NP cluster arrays remains a significant challenge. This paper presents a novel strategy to prepare large-scale Au NP cluster arrays based on colloidal lithography and template-guided self-assembly technique. The NPs arrays are fabricated by introducing Au NPs onto the quaternized poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brush templates via electrostatic interaction. The number of Au NPs in cluster can be arbitrarily tuned by changing the surface area of the polymer templates created by colloidal lithography, which resulted in tunable plasmonic properties. The prepared Au NP cluster arrays were used for surface enhanced Raman scattering (SERS) and the SERS properties of the Au NP cluster arrays were studied.

Design and synthesis of dodecahedral carbon nanocages incorporated with Fe3O4

Novel dodecahedral carbon nanocages (NCs) modified with Fe3O4 nanoparticles (Fe3O4/C NCs) were constructed by utilizing a zeolitic imidazolate framework (ZIF-8) as the template and polydopamine (PDA) as the carbon source. The obtained nanocages not only display specific morphology with controllable feature structures, but also possess a large surface area and inner cavity. This unique structure of the nanocages and special synthesis approach make Fe3O4 NPs homogenously distributed in the system, which further enriched the function of the carbon nanocages. Due to the integrated functional nanoparticles and large interior of such specific structures, the as-prepared Fe3O4/C NCs are further used as anode materials in lithium ion batteries (LIBs), which exhibit high activity in lithiation/delithiation cycling process and stable capacity retention. The nanocages we prepared may provide a train of thought to construct a series of hollow carbon nanostructures with functional materials incorporated.