Rational design, synthesis, and applications of carbon-assisted dispersive Ni-based composites

Herein, we review recent developments in the rational design and engineering of various carbon-assisted dispersive nickel-based composites, and boosted properties for protein adsorption and nitroaromatics reduction.

Au-Fe3O4 decorated polydopamine hollow nanoparticles as high performance catalysts with magnetic responsive properties

We demonstrated a simple approach for fabricating Au-Fe₃O₄/PDA hollow nanoparticles as high-performance catalysts for water purification. The polydopamine (PDA) shell was in situ formed on the silica surface from self-polymerization, which acts as a medium support for coupling with metal ions (for Fe₃O₄ nanoparticle deposition) as well as a reducing agent and stabilizer for Au nanoparticle reduction and deposition. A step of simultaneous Fe₃O₄ nanoparticle deposition and silica core removal under alkaline conditions is first introduced in this study. This process significantly simplifies previous strategies which typically require the use of poisonous agents such as hydrogen fluoride or additional complicated post-treatment steps. Under optimized conditions, the Au-Fe₃O₄/PDA hollow nanoparticles show a high saturation magnetization of 18.8 emu g^-1 and an excellent catalytic performance for the rapid reduction of p-nitrophenol with the reaction kinetic constant of 0.34 min^-1. This catalyst can be easily recovered using a permanent magnet and recycled eight times with a high catalytic cycle stability. The strategy presented in this work provides a facile and versatile approach towards designing complicated Au-Fe₃O₄/PDA hollow nanostructures, which might have great potential for many applications within biological, energy, and environmental technologies.

Zeolitic Imidazolate Framework-Based Composite Incorporated with Well-Dispersed CoNi Nanoparticles for Efficient Catalytic Reduction Reaction

Incorporation of metal nanocatalysts within a well-defined porous support is of great importance for stabilizing unstable metal nanocatalysts, so that they display an effective and long-lasting catalytic activity. In particular, metal-organic frameworks (MOFs) with a wide range of structures serve as excellent porous supports for stabilizing unstable nanocatalysts. In addition, the development of inexpensive metal nanocatalysts is necessary to replace expensive noble metal nanocatalysts. Herein, we report on a simple method for the preparation of porous MOF-based or carbon-based composites incorporated with catalytically active CoNi alloy nanoparticles. CoNi alloy nanoparticles were produced from the concurrent reduction of Co and Ni ions existing within a zeolitic imidazolate framework (ZIF)-based precursor material during the thermal treatment. In particular, a part of the highly porous ZIF was preserved during the thermal treatment at 400 °C, which eventually resulted in a composite of ZIF and CoNi (CoNi@ZIF). The resulting CoNi@ZIF showed excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol. The synergy between the highly porous ZIF support and the well-dispersed CoNi nanoparticles within CoNi@ZIF provided an outstanding catalytic performance, even with inexpensive transition-metal nanocatalysts. Moreover, the catalytic activity of CoNi@ZIF was well conserved even after five consecutive reactions.

Templated synthesis of nickel nanoparticles embedded in a carbon layer within silica capsules

The encapsulation of small non-noble metal nanoparticles (NPs) within an inorganic layer has received considerable attention owing to their enhanced stability and high catalytic activity. Using a combination of emulsion-free polymerization, inner RF-Ni2+ and outer SiO2 coating, and subsequent carbonization treatment, herein, we have fabricated worm-like structured Ni-based composites in which a high density of nickel NPs are embedded in a carbon layer and also entrapped by SiO2 nanocages. We find that the carbonization temperature plays a vital role in adjusting the size of the Ni NPs. A detailed examination of the encapsulated nickel particles synthesized at 700 °C exhibited the best performance on the catalysis of the reduction of 4-NPs. Moreover, owing to the good alloying ability of the Ni NPs with noble metal NPs, the Ni-Pd alloy NPs are also entrapped in the SiO2 nanocages, which exhibit better performance on the catalysis than the Ni-based composites. The encapsulation of Ni-Pd alloys within SiO2 nanocages also improves stability against agglomeration and metal separation during catalytic operation.

Bioaccumulation investigation of bisphenol A in HepG2 cells and zebrafishes enabled by cobalt magnetic polystyrene microsphere derived carbon based magnetic solid-phase extraction

A magnetic solid-phase extraction (MSPE) technique coupled with high performance liquid chromatography (HPLC) was developed and used for bioaccumulation investigation of bisphenol A (BPA) in HepG2 cells and zebrafishes. Cobalt magnetic polystyrene microsphere derived carbon (C-Co@PST) as an adsorbent was prepared by in situ polymerization reaction and further annealing treatment. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction were employed to confirm successful synthesis of C-Co@PST. A series of extraction parameters including the amount of the sorbent, the type of elute, extraction time and elution time were investigated to achieve high extraction efficiency. C-Co@PST based MSPE combined with HPLC was successfully established for bioaccumulation research of BPA in living creatures. It was found that the bioconcentration values of BPA in HepG2 cells underwent an increase, then a decrease, and finally reached an equilibrium level of 11.60 μg kg-1 at 8 h. The concentration of BPA in zebrafishes increased ranging from 6.05 μg kg-1 to 31.84 μg kg-1 over a culture time from 1 h to 12 h. Furthermore, linear and exponential models were employed to analyse the bioconcentration variation of BPA in organisms over the exposure time. Mathematical models have been developed to predict the transfer characteristics of BPA.

Carbon supported PdNi alloy nanoparticles on SiO2 nanocages with enhanced catalytic performance

Here we present a simple approach for the fabrication of Pd–Ni alloy nanoparticles embedded in a carbon layer on raspberry-like SiO₂ hollow nanocages (SiO₂@C-PdNi).

Rational synthesis of a ZIF-67@Co–Ni LDH heterostructure and derived heterogeneous carbon-based framework as a highly efficient multifunctional sulfur host

A core-shelled heterogeneous carbon-based framework induced a smooth “immobilization–diffusion–conversion–deposition” process of polysulfides and significantly improved the performance of Li–S batteries.

One dimensional hierarchical nanoflakes with nickel-immobilization for high performance catalysis and histidine-rich protein adsorption

Herein, we described a facile strategy for the controllable synthesis of three dimensional hierarchical nickel based composites, which exhibited excellent performance on catalysis and protein adsorption.