Hanani Yazid

Optical absorption and photoluminescence studies of gold nanoparticles deposited on porous silicon.

We present an investigation on a coupled system consists of gold nanoparticles and silicon nanocrystals. Gold nanoparticles (AuNPs) embedded into porous silicon (PSi) were prepared using the electrochemical deposition method. Scanning electron microscope images and energy-dispersive X-ray results indicated that the growth of AuNPs on PSi varies with current density. X-ray diffraction analysis showed the presence of cubic gold phases with crystallite sizes around 40 to 58 nm. Size dependence on the plasmon absorption was studied from nanoparticles with various sizes. Comparison with the reference sample, PSi without AuNP deposition, showed a significant blueshift with decreasing AuNP size which was explained in terms of optical coupling between PSi and AuNPs within the pores featuring localized plasmon resonances.

Synthesis of Chitosan-Gold Nanoparticles for Drug Delivery

Gold nanoparticles (Au NPs) have potential applications in catalysis, drug delivery, sensors and environmental remediation. This wide range application is due to its amenability of synthesis and functionalization, less toxicity and ease of detection. The present work focuses on functionalization of Au NPs with chitosan for further application in biomedical research. Gold nanoparticles (Au NPs) functionalized chitosan were prepared by reducing gold salt solution at various pH medium in the presence of sodium borohydride. The effect of pH and chitosan concentration on the Au particle size and distribution are studied. The results revealed the dependence of Au particle size on the pH of the solution. The smallest Au particle size is found to form in a range of 10.22 ± 2.96 nm at 0.2% chitosan concentration. In this study, we anticipate the Au NPs functionalized chitosan can be used for drug delivery applications.

Synthesis of gold nanoparticles on multi-walled carbon nanotubes (Au-MWCNTs) via deposition precipitation method

Carbon nanotubes (CNTs) have received impressive consideration as support materials of noble metal catalysts in heterogeneous catalysis due to their good mechanical strength, large surface area and good durability under harsh conditions. The interaction between CNTs and noble metal nanoparticles (NPs) gives an unusual unique microstructure properties and or modification of the electron density of the noble metal clusters, and enhances the catalytic activity. In this study, the MWCNTs were first treated with a mixture of concentrated sulfuric and nitric acid by sonication to improve its dispersibility and to introduce the carboxylic (-COOH) groups on CNTs surfaces. Gold nanoparticles (Au NPs) on multiwalled carbon nanotubes (MWCNTs) were synthesized by the deposition precipitation (DP) method as this method is simpler, low cost, and excellent method. Then, the effect of reducing agent (NaBH4) on gold distribution on the support of MWCNTs was also studied. Dispersion test, Fourier Transform Infrared spectroscopy (FTIR) and Field Emission Scanning Electron Microscope (FESEM) are all used to characterize the functionalized MWCNTs (fCNTs) and the Au NPs-fCNTs catalyst. There are three important peaks in functionalized MWCNTs which correspond to C=O, O-H, and C-O absorption peaks, as a result of the oxidation of COOH groups on the surface of CNTs. The absorption band at 1717 cm−1 is corresponded to C=O stretching of COOH, while the absorption bands at 3384 cm−1 and 1011cm−1 are associated with O–H bending and C–O stretching, respectively. Surface morphology of Au NPs-fCNTs R4 and Au NPs- fCNTs WR catalyst by FESEM showed that the Au NPs of 19.22 ± 2.33 nm and 23.05 ± 2.57 nm size were successfully deposited on CNTs, respectively.Carbon nanotubes (CNTs) have received impressive consideration as support materials of noble metal catalysts in heterogeneous catalysis due to their good mechanical strength, large surface area and good durability under harsh conditions. The interaction between CNTs and noble metal nanoparticles (NPs) gives an unusual unique microstructure properties and or modification of the electron density of the noble metal clusters, and enhances the catalytic activity. In this study, the MWCNTs were first treated with a mixture of concentrated sulfuric and nitric acid by sonication to improve its dispersibility and to introduce the carboxylic (-COOH) groups on CNTs surfaces. Gold nanoparticles (Au NPs) on multiwalled carbon nanotubes (MWCNTs) were synthesized by the deposition precipitation (DP) method as this method is simpler, low cost, and excellent method. Then, the effect of reducing agent (NaBH4) on gold distribution on the support of MWCNTs was also studied. Dispersion test, Fourier Transform Infrared spectro...

Synthesis and Morphological Characterization of Gold Nanoparticles (AuNPs) Supported on Anodized Titanium Oxide (TiO2) Nanotubes

Increasing interest of attachment gold nanoparticles (AuNPs) on titanium oxide (TiO2) nanotubes has been devoted to give tremendous properties suitable for catalysis application. Nevertheless, achieving precise control of attachment AuNPs on the TiO2 nanotubes substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto electrochemically-anodized TiO2 nanotubes by deposition-precipitation method. The structural and elemental characterizations of the supported AuNPs are carried out by means of field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX) analysis. The FESEM image showed the anodized TiO2 nanotube with good morphological structure is successfully fabricated at a voltage of 20 V and in a mixture electrolyte of ethylene glycol containing 0.5 wt% ammonium fluoride solutions with an average nanotubes diameter of 87 nm. Meanwhile, the attachment of AuNPs on the fabricated TiO2 nanotubes has been effectively achieved for both calcined and uncalcined samples. The EDX analysis has confirmed the deposition of AuNPs over the TiO2 nanotubes. The results showed that we had succeeded in synthesizing the AuNPs supported on the anodized TiO2 nanotubes, which provide superior metal-metal oxide synthetic devices for diverse applications.

Soft and Hard Surface Manipulation of Nanoporous Anodic Aluminum Oxide (AAO)

Nanoporous materials with straight channels have attracted considerable interest due to their unique physical properties and many potential applications such as separation, sensing, biomedical and electronics. For the last few decades, nanoporous alumina or anodic aluminium oxide (AAO) membrane is gaining attention due to its broad applicability in various applications. The unique properties of AAO membrane coupled with tunable surface modification and properties is playing an increasingly important platform in a diverse range of applications such as separation, energy storage, drug delivery and template synthesis, as well as biosensing, tissue engineering and catalytic studies. This chapter aims to introduce the recent advances and challenges for surface manipulation of AAO following the ‘soft’ and ‘hard’ modification strategies. The functions of these modified nanostructures materials and latest important applications are evaluated with respect to improved performance and possible implications of those strategies for the future trends of surface engineering are discussed.

Synthesis and Characterization of Gold Nanoparticles Grafted on Nanoporous Anodic Aluminum Oxide (AAO) Membrane

Gold nanoparticles (Au NPs) supported on nanoporous anodic aluminium oxide (AAO) membrane has been successfully prepared by direct anionic exchange for further application in catalysis. The nanoporous AAO membrane is immersed in HAuCl4 solution at different pH to achieve gold nanoparticles grafted on AAO (Au-AAO). It was found that the pH of the HAuCl4 solution played an important role for controlling the size of Au NPs as well as the amount of Au depositing on the surface of AAO membrane. The prepared Au-AAO membranes were characterized by diffuse reflectance UV-Vis spectroscopy, high-resolution scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy.