Tuan Anh Pham

Facile covalent immobilization of cadmium sulfide quantum dots on graphene oxide nanosheets: preparation, characterization, and optical properties

A facile approach for the preparation of a novel hybrid material containing graphene and an inorganic semiconducting material, cadmium sulfide quantum dots (CdS QDs), is demonstrated for the first time. First, amino-functionalized CdS QDs were prepared by modifications of the kinetic trapping method. Then, pristine graphite was oxidized and exfoliated to obtain graphene oxide nanosheets (GONS), which were then acylated with thionyl chloride to introduce acyl chloride groups on their surface. Subsequently, immobilization of the CdS QDs on the GONS surface was achieved through an amidation reaction between the amino groups located on the CdS QDs surface and the acyl chloride groups bound to the GONS surface. Fourier transform infrared spectroscopy (FT-IR), (1)H nuclear magnetic resonance ((1)H-NMR), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and energy dispersive x-ray (EDX) spectroscopy were employed to investigate the changes in the surface functionalities, while high resolution transmission electron microscopy (HR-TEM) and field emission scanning electronic microscopy (FE-SEM) were used to study the morphologies and distribution of the CdS QDs on the GONS surface. Thermogravimetric analysis (TGA) was employed to characterize the weight loss of the samples on heating. Photoluminescence (PL) measurements were used to study the optical properties of the prepared CdS QDs and the CdS-graphene hybrid material.

Water-Dispersible Multi-Walled Carbon Nanotubes and Novel Hybrid Nanostructures

Water-dispersible multi-walled carbon nanotubes (MWNTs) were successfully prepared by the chemical grafting of acylated MWNTs with adenosine. The MWNTs were first purified and oxidized in order to obtain carboxylic acid funcionalized MWNTs, which was further acylated with thionyl chloride to give acyl chloride bound MWNTs. Then, adenosine was grafted onto the surface of nanotubes by chemical functionalization via esterification or amidation reaction. Further, novel hybrid nanostructures were synthesized by reaction of hydroxyl groups between adenosine-functionalized MWNTs and boronic acid functionalized gold nanoparticles to form boronate ester linkages that anchor gold nanoparticles onto the external surface of functionalized nanotubes.

Facile Preparation of Water-Dispersible Adenosine-Functionalized Graphene Nanosheets

Water-dispersible graphene nanosheets were achieved by a simple three-step process. First, pristine graphite was oxidized and exfoliated to obtain graphene oxide, which was further acylated with thionyl chloride to introduce acyl chloride groups on the surfaces. Second, graphene oxide was covalently functionalized with an environment-friendly reagent, namely, adenosine. Subsequently, adenosine-functionalized graphene oxide was reduced to obtain graphene nanosheets by using NaBH4 as a reducing agent. This approach facilitates graphene nanosheets that have a combination of stable aqueous dispersions and an electrical conductivity that are much better in comparison to graphene oxide, offering a great flexibility for further applications.

Preparation of Gold Nanoparticles/Graphene Hybrid Using 4-Mercaptobenzoyl Functionalized Graphene Nanosheets as Templates

The authors report an effective and simple route to prepare gold nanoparticles/graphene hybrid via the way of chemical functionalization. First, graphene nanosheets were functionalized with 4-mercaptobenzonic acid via a direct Friedel-Crafts acylation reaction in a polyphosphoric acid/phosphorus pentoxide medium. Second, gold nanoparticles were prepared from the in situ reduction of gold (III) chloride trihydrate by sodium borohydride. Subsequently, gold nanoparticles were decorated on graphene surface via the well-developed Au-S chemistry. High-resolution transmission electron microscopy and atomic force microscopy were employed to investigate the distribution of gold nanoparticles on the surfaces of graphene nanosheets.

Water dispersibility of gluconate functionalised multiwalled carbon nanotubes and facile strategy for construction of hybrid nanostructures

Abstract Water dispersibility of multiwalled carbon nanotubes (MWNTs) has been achieved by functionalisation of the MWNTs with sodium gluconate (SOGL). The chemical grafting of SOGL onto the surfaces of MWNTs was carried out by producing acyl chloride groups on the oxidised MWNTs, and then, anhydride bond was formed between the SOGL and functionalised MWNTs. In addition, we also studied the chemical stability of anhydride bond in acid solution, base solution and neutral water with pH values of 5, 9 and 7 respectively. On the other hand, boronic acid functionalised gold nanoparticles were prepared for the decoration of gold nanoparticles to yield novel hybrid nanostructures via the formation of boroester bonds. The resulting novel hybrid nanostructures were investigated in detail using various techniques, including Fourier transform infrared spectroscopy, UV visible spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy.