Xiaobin Fan

Sulfonated graphene as water-tolerant solid acid catalyst

Acid catalysts are essential for various chemical reactions in the industrial hydrocarbon chemistry. Sulfonated carbon has shown promising application as a new, cheap and environmentally friendly solid acid catalyst. In this study, we prepared the sulfonated graphene acid catalyst, and it was characterized by electron microscopy, Raman spectroscopy, solid state 13C MAS NMR, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Catalytic hydrolysis of ethyl acetate shows that the sulfonated graphene has highly catalytic activity and can be repetitively used as a water-tolerant solid acid catalyst.

Graphene supported Au-Pd bimetallic nanoparticles with core-shell structures and superior peroxidase-like activities

AucorePdshell (Au@Pd) bimetallic nanoparticles of sub-10 nm were successfully dispersed on graphene by a simple one step reducing method. The Au@Pd nanoparticles–graphene (Au@Pd–G) hybrids were characterized by high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, energy X-ray spectroscopy and electronic energy loss spectroscopy. Evaluation of their catalytic performance demonstrates the Au@Pd–G hybrids have extraordinary peroxidase activity as catalysts.

Advanced Graphene‐Based Binder‐Free Electrodes for High‐Performance Energy Storage

The increasing demand for energy has triggered tremendous research effort for the development of high-performance and durable energy-storage devices. Advanced graphene-based electrodes with high electrical conductivity and ion accessibility can exhibit superior electrochemical performance in energy-storage devices. Among them, binder-free configurations can enhance the electron conductivity of the electrode, which leads to a higher capacity by avoiding the addition of non-conductive and inactive binders. Graphene, a 2D material, can be fabricated into a porous and flexible structure with an interconnected conductive network. Such a conductive structure is favorable for both electron and ion transport to the entire electrode surface. In this review, the main processes used to prepare binder-free graphene-based hybrids with high porosity and well-designed electron conductive networks are summarized. Then, the applications of free-standing binder-free graphene-based electrodes in energy-storage devices are discussed. Future research aspects with regard to overcoming the technological bottlenecks are also proposed.

Poly(amidoamine) modified graphene oxide as an efficient adsorbent for heavy metal ions

Poly(amidoamine) modified graphene oxide was prepared via a grafting-from method and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Evaluation of its adsorption capacity for heavy metal ions demonstrated that the poly(amidoamine) modified graphene oxide had superior adsorption ability towards heavy metal ions such as Cu2+, Zn2+, Fe3+, Pb2+ and Cr3+.

Isolation of carbon nanohorn assemblies and their potential for intracellular delivery

Attributed to its distinctive dahlia-flowerlike structure and already desirable size (usually <100 nm), carbon nanohorn assemblies (CNHs), a new member of the fullerene family, are a potential vehicle for intracellular delivery. This paper shows that isolated CNHs and nanoscale CNH agglomerates can be successfully isolated by a copolymer (Gum Arabic) through steric stabilization. In vitro study shows that the modified CNHs are nontoxic and may be used as a promising vehicle for intracellular delivery.

Palladium Complex Immobilized on Graphene Oxide as an Efficient and Recyclable Catalyst for Suzuki Coupling Reaction

A graphene supported palladium (Pd) catalyst for Suzuki coupling reaction has been successfully prepared by immobilizing Pd(II) onto graphene oxide surface through the in situ coordination interaction with aminosilane ligand spacers. This catalyst showed high catalytic activities in the Suzuki coupling of various aryl halides and phenylboronic acid. Moreover, it could be readily recycled and reused for several times without discernible loss of its catalytic activity.Graphical Abstract

Poly(N-isopropylacrylamide) on two-dimensional graphene oxide surfaces

Poly(N-isopropylacrylamide) (PNIPAM)–graphene oxide (GO) hybrids were successfully prepared. The structural reorganization behavior of GO–PNIPAM is dependent on the water content in the GO–PNIPAM hybrids. Reversible switching of its wettability on exposure to NIR light was also demonstrated.

Enhanced hydrogenation of olefins and ketones with a ruthenium complex covalently anchored on graphene oxide

Graphene oxide (GO) is a promising support for anchoring homogeneous metal complexes because of its two-dimensional structure, huge surface area and diversity for chemical functionalizations. In this study, a ruthenium supported catalyst has been synthesized by covalently bonding a ruthenium complex (RuCl2(PPh3)3) onto the GO surface through coordination interaction with aminosilane ligand spacers. The supported catalyst showed enhanced catalytic performance towards hydrogenation of olefins and ketones compared with the homogeneous analogue, and it could be readily recycled and reused several times without discernible loss of its activity.

Robust and smart gold nanoparticles: one-step synthesis, tunable optical property, and switchable catalytic activity

We have developed a one-step method to prepare robust and smart gold nanoparticles (AuNPs) utilizing poly(N-isopropylacrylamide) (PNIPAAm)-grafted dextran (DexPNI) via a “grafting-onto” approach. Using NaBH4 as a reducing agent, and DexPNI as a nucleating and stabilizing agent, the AuNPs can be obtained at ambient temperature within a short reaction time. Different features of AuNPs, such as their morphologies, optical properties and temperature-responsive behaviours are found to be dependent on the dosage of the gold precursor. The DexPNI-stabilized AuNPs not only show excellent stability against heat, high salt concentration and extreme pH, but could also be readily redispersed after freeze-drying. UV measurements and kinetic analysis of the AuNPs-catalyzed reduction of 4-nitrophenol at different temperatures illuminated that the optical properties and catalytic activity of AuNPs are closely related to temperature. Compared with previously reported diffusion-regulated nanoreacters, our AuNPs provide a unique opportunity to control the reaction rate in an inverse temperature-responsive manner at 32–35 °C, and further switch off the reaction at temperatures higher than 35 °C. These temperature-responsive properties could be used to create a smart sensor and catalyst, acting as an optical temperature alarm and recloser when the reaction temperature accidentally goes beyond the limit value. By using monomers and colloidal precursors other than NIPAAm and HAuCl4, it will be straightforward to extend the present route to build a variety of robust and smart nanomaterials with unprecedented properties.

Combining palladium complex and organic amine on graphene oxide for promoted Tsuji–Trost allylation

In this study, we develop a facile strategy to combine an organic amine with a palladium complex on graphene oxide (GO) as a cooperative catalyst for Tsuji–Trost allylation. A tertiary amine and palladium–diamine complex are simultaneously immobilized on a GO support through silylation and further in situ coordination processes. PdCl2 is employed as the palladium precursor, with no necessity for extra coordination ligands. Various characterizations confirm the successful preparation of the cooperative supported catalyst (GO–NEt2–2N–Pd). Systematic investigation reveals the immobilized palladium–diamine complex (GO–2N–Pd) with very low Pd loading is effective for Tsuji–Trost allylation, and incorporation of the tertiary amine shows a significant promoting effect towards the catalytic activity. GO–NEt2–2N–Pd can be readily recovered and recycled several times without reduction of its efficiency. Its excellent performance should be ascribed to synergistic catalysis effect, excellent support properties, and robust immobilization interaction.