Fang Cui

Preparation of yolk–shell FexOy/Pd@mesoporous SiO2 composites with high stability and their application in catalytic reduction of 4-nitrophenol

Yolk-shell composites with a movable Fe(x)O(y) core and mesoporous SiO2 (mSiO2) shell, together with Pd nanoparticles uniformly anchoring on the inner surface, were prepared. The structure and composition of as-prepared catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller measurement and Fourier-transform infrared spectroscopy, respectively. They are ideal candidates as nanoreactors for heterogeneous catalysis due to their special structure. The catalytic performance of Fe(x)O(y)/Pd@mSiO2 composites was studied by the reduction of 4-nitrophenol with NaBH4 as a reducing agent. Their reaction rate constant was calculated according to the pseudo-first-order reaction equation. The catalysts could be easily recycled by an external magnetic field due to their superparamagnetic property. Besides good catalytic property, another merit of Fe(x)O(y)/Pd@mSiO2 composites was high stability. We have compared the stability between Fe(x)O(y)/Pd@mSiO2 and Fe3O4@C/Pd composites by ultrasonic treatment and HNO3 solution etching, the stability of the former was much better than the later.

A simple way to prepare Au@polypyrrole/Fe3O4 hollow capsules with high stability and their application in catalytic reduction of methylene blue dye

Metal nanoparticles are promising catalysts for dye degradation in treating wastewater despite the challenges of recycling and stability. In this study, we have introduced a simple way to prepare Au@polypyrrole (PPy)/Fe3O4 catalysts with Au nanoparticles embedded in a PPy/Fe3O4 capsule shell. The PPy/Fe3O4 capsule shell used as a support was constructed in one-step, which not only dramatically simplified the preparation process, but also easily controlled the magnetic properties of the catalysts through adjusting the dosage of FeCl2·4H2O. The component Au nanoparticles could catalyze the reduction of methylene blue dye with NaBH4 as a reducing agent and the reaction rate constant was calculated through the pseudo-first-order reaction equation. The Fe3O4 nanoparticles permitted quick recycling of the catalysts with a magnet due to their room-temperature superparamagnetic properties; therefore, the catalysts exhibited good reusability. In addition to catalytic activity and reusability, stability is also an important property for catalysts. Because both Au and Fe3O4 nanoparticles were wrapped in the PPy shell, compared with precursor polystyrene/Au composites and bare Fe3O4 nanoparticles, the stability of Au@PPy/Fe3O4 hollow capsules was greatly enhanced. Since the current method is simple and flexible to create recyclable catalysts with high stability, it would promote the practicability of metal nanoparticle catalysts in industrial polluted water treatment.

A simple way to prepare Pd/Fe3O4/polypyrrole hollow capsules and their applications in catalysis

Preparation of catalysts with good catalytic activity and high stability, together with magnetic separation property, in a simple way is highly desirable. In this paper, we reported a novel strategy to construct magnetic recyclable hollow capsules with Pd and Fe3O4 nanoparticles embedded in polypyrrole (PPy) shell via only two steps: first, synthesization of Pd nanoparticles, preparation of Fe3O4 nanoparticles, and formation of PPy shell were finished in one-step on the surface of polystyrene (PS) nanospheres; then, the PS core was selectively removed by tetrahydrofuran. The Pd/Fe3O4/PPy hollow capsules exhibited good catalytic property in reduction of 4-nitrophenol with NaBH4 as reducing agent, and the reaction rate constants were calculated through pseudo-first-order reaction equation. Due to incorporation of Fe3O4 nanoparticles, the catalysts could be quickly separated from the reaction solution by magnet and reused without obvious catalytic loss. Besides catalytic property and reusability, their stability was also examined by HNO3 etching experiment. Compared with bare Pd and Fe3O4 nanoparticles, the stability of both Pd and Fe3O4 nanoparticles in hollow capsules was largely improved owing to the protection of PPy shell. The good catalytic performance, ease of separation, high stability and especially a simple preparation procedure, made Pd/Fe3O4/PPy hollow capsules highly promising candidates for diverse applications.

One Step Preparation of Reduced Graphene Oxide/Pd–Fe3O4@Polypyrrole Composites and Their Application in Catalysis

The simple preparation of catalysts with superior catalytic activity and good reusability is highly desirable. Herein, we report a novel strategy to construct reduced graphene oxide (rGO)/Pd-Fe3 O4 @polypyrrole (PPy) catalysts with Pd and Fe3 O4 nanoparticles anchored on a rGO nanosheet surface and wrapped in a PPy shell. The synthesis and assembly of both the Pd and Fe3 O4 nanoparticles, the preparation of the PPy layer, and the reduction of graphene oxide nanosheets were finished in one step. In the system, the PPy layer not only prevented aggregation of Pd and Fe3 O4 nanoparticles, but also generated a synergistic effect with precursor Pd(2+) ions, which led to a high dispersity of as-prepared Pd nanoparticles. Although the procedure was simplified to one step, the catalytic activity and reusability were not sacrificed. In the reduction of 4-nitrophenol, their catalytic performance was better than that in recent reports. Moreover, the catalysts showed good reusability owing to their magnetic properties.

Facile synthesis of ultrasmall TiO2 nanocrystals/porous carbon composites in large quantity and their photocatalytic performance under visible light

In this paper, we demonstrate a facile and scalable route to the preparation of composites containing ultrasmall TiO2 nanocrystals and porous carbon matrix. In this method, the titanium ions are covalently introduced to polymer chains and transformed into TiO2 nanocrystals directly in solid matrices, which allows the generation of well dispersed TiO2 nanocrystals with small size in the entire carbon matrix. To our knowledge, this is the first time that ultrasmall TiO2 nanocrystals are incorporated into a bulk porous carbon matrix. In comparison with pure TiO2 particles, the composites exhibit significant improvement in photocatalytic degradation of methyl blue under visible light irradiation, which might be attributed to the ultrasmall size of TiO2 nanocrystals as well as the high separation efficiency of photogenerated electrons and holes based on the synergistic effect between TiO2 nanocrystals and carbon matrices. Furthermore, the composites could be easily recycled without obvious activity loss.

Janus building block-enabled fabrication of dual metal equipped coordination polymers: an ideal precursor for noble metal/metal oxide nanocomposites with excellent catalytic performance

Coordination polymer nanoribbons equipped with dual metal ions are fabricated by using a Janus building block, which combines two parts with distinct characters, a chemically hard group to assemble the host network with Co2+ ions, and a chemically soft unit to subsequently anchor noble ions. By judiciously adjusting the desolvation process, the 1D assembly of the Janus building blocks with Co2+ ions can be readily achieved. The structure analysis and formation mechanism study of the nanoribbons provide important guidance on the design and assembly manipulation of other bifunctional molecules. Furthermore, the dual metal ion equipped nanoribbons can act as ideal precursors for 1D Pd/Co3O4 nanocomposites with excellent catalytic activity, improved durability and magnetic separation ability.

Self-Catalytic Synthesis of CuO@SiO2 Nanocomposites under Neutral Condition and Its Catalytic Performance

Herein, we reported a novel strategy to synthesize CuO@SiO2 nanocomposites under neutral conditions with the self-catalysis effect of APTES and CuBA2 as proper precursor. No additional acid or alkali was required as catalyst during the entire process. On the other hand, the catalytic properties of CuO@SiO2 composites were evaluated by catalyzing the reduction of 4-nitrophenol using NaBH4 as the reducing agent. The results revealed that the products exhibit excellent catalytic property and cycling performance.