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The present study reports a simple hydrothermal approach for conveniently synthesizing cupric oxide (CuO) nanobelts without a templating agent. Electron microscopic studies indicate that these nanobelts have a wide stem (300–500 nm) and sharp tip (80–150 nm), with lengths up to 6 µm. X-ray diffraction patterns confirm the formation of a single monoclinic phase of CuO. A possible reaction mechanism was proposed to account for the growth of nanobelts. The optical properties of the products were investigated using UV–vis spectroscopy and photoluminescence (PL) measurement. The direct band gap energy for CuO nanobelts was estimated to be 3.2 eV, which is larger than the value of bulk CuO and likely related to quantum size effects. The magnetic properties of CuO nanobelts measured at room temperature exhibited a ferromagnetic behavior with a coercive force ( Hc ) of 93.35 Oe, whereas a paramagnetic behavior was observed in liquid nitrogen. The magnetic behavior was discussed in terms of CuO morphology effects.

The synthesis and surface properties of a composite material consisting of porous silicon/magnetite nanoparticles (PSi/Fe3O4 NPs) are demonstrated. PSi layers with intermediate pore size (∼100 nm) are prepared by electrochemical porosification of n-type Si wafer in a hydrofluoric acid-containing oxidizing agent and surfactant. The intrinsically luminescent PSi templates are infiltrated with ferromagnetic Fe3O4 NPs grown by a simple hydrothermal approach with average sizes ranging from 8 to 30 nm. The photoluminescence intensity of magnetic nanocomposite was enhanced after Fe3O4 loading, probably due to the recombination of photoexcited carriers within the nanocrystallites. Magnetization measurement for the nanocomposites indicated that the magnetic nanoparticles retain their ferromagnetic characteristic at room temperature. The nanocomposites have been characterized by various techniques including, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and magnetic measurements. The biocompatibility of both components and the ability to tailor the magnetic properties of the composite might be useful for magnetic and biomedical applications.

Novel nanocomposites of conducting polymers and mesoporous silicon with pore sizes

An eco-friendly chemical reduction method was successfully used for the preparation of chitosan (CTS) composite films loaded with silver nanoparticles (AgNPs) by self assembly method using poly(ethylene glycol) as both reducing and stabilizing agent. UV-Vis spectra of the prepared chitosan loaded silver nanoparticles (CTSLAg) films reveal that full reduction of silver ions to silver nanoparticles takes place at 90 °C. The effect of reaction conditions on the silver nanoparticles formation was investigated using UV-Vis spectrophotometer. The morphology of the films was tested by scanning electron microscopy (SEM). The DSC curves showed that the CTSLAg film had a favorable compatibility and heat stability. AgNPs were confirmed by XRD and UV-Vis spectroscopy. The TEM findings revealed that the silver nanoparticles synthesized were spherical in shape with uniform dispersal, and by increasing CTS:PEG ratio larger silver nanoparticles could be obtained. The results of antibacterial study reveal that the prepared nanocomposite films exhibited potential inhibition.

Polyethylene glycol (PEG)-stabilized Palladium (Pd) nanoparticles have been successfully synthesized by a simple hydrothermal approach. The as-prepared catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption-desorption measurements. Pd nanoparticles show a high degree of dispersion in PEG with a small average particle size distribution in the range of 3–6 nm. The Pd/PEG catalyst exhibited a remarkable catalytic activity toward selective hydrogenation of crotonaldehyde and oxidation of benzene in liquid phase under mild conditions. The catalyst could be easily removed from the reaction mixture and its recyclability was possible for ten times for crotonaldehyde and two times for benzene. The catalytic performance was found to depend essentially on the catalyst and target concentrations and reaction time.

Titania–silica (TiO 2 –SiO 2 ) photocatalyst was prepared by a modified sol–gel technique. Titania sol was firstly synthesized by acid hydrolysis of a TiCl 4 precursor instead of titanium alkoxides. The titania sol was further modified with SiO 2 to obtain a modified catalyst. The as-prepared TiO 2 –SiO 2 catalyst demonstrated a remarkable photocatalytic activity toward degradation of cyanide and heavy metals removal (Cr(III), Co(II) and Pb(II)). The influence of the preparation parameters; the reaction time, the calcination temperature and time, the [H + ]/[Ti] ratio, the pH value and the acid concentration on the structural and chemical properties of the catalyst was investigated in details. The catalytic performance was found to depend essentially on the catalyst and target concentrations and the reaction time. The as-synthesized catalyst was characterized by a variety of techniques including surface area measurement, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) transmission electron microscopy (TEM) and ultraviolet–visible (UV–vis) spectroscopy measurements. Results of the synthesis and characterization of TiO 2 –SiO 2 catalyst and its photocatalytic performance are presented and thoroughly discussed.

A nanostructured CoPt magnetic film was deposited from a single electrolyte into porous silicon layer by an electrochemical technique, followed by annealing at 600 °C in Ar atmosphere during which the CoPt alloy was converted to L10 ordered phase. Porous silicon with pore diameter between 5 and 100 nm was firstly fabricated by galvanostatic anodization of n-type silicon wafer in the presence of CrO3 as oxidizing agent and ethanol or sodium lauryl sulfate as surfactants. The role of the surfactant on the produced pore size and morphology was investigated by means of UV–vis spectra. As-formed porous silicon was consequently used as a template for the electrodeposition of magnetic CoPt film. The phase formation, microstructure and the magnetic properties were fully analyzed by XRD, FE-SEM, EDS and VSM measurements. It was found that, upon annealing the coercivity was significantly increased due to the transformation to the L10 ordered structure. The saturation magnetization and remanence ratio were also found to increase, indicating no loss of Co content or oxidation reaction after the annealing. Results of synthesis and characterization of CoPt/porous silicon nanocomposite are addressed and thoroughly discussed.

Sized-controlled YVO4 nanoparticles have been synthesized by a simple hydrothermal method by changing hydrothermal time from 4 to 24 h. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (Brunauer–Emmett–Teller (BET)), and ultraviolet–visible spectroscopy (UV–vis) measurements. The results showed that the size of as-synthesized YVO4 nanoparticles was in the range of 11–40 nm and was extremely dependent on the hydrothermal time. Photocatalytic measurement showed that the YVO4 nanoparticles with particle size of about 11 nm (prepared by 4 h hydrothermal time) possess superior photocatalytic properties in the decolorization of direct blue dye. Due to simple preparation, high photocatalytic oxidation of direct blue dye and low cost, the YVO4 photocatalyst is a potential candidate for pollutants removal and will find wide application in the coming future in photocatalytic oxidation processes. The overall kinetics of photodegradation of direct blue dye using YVO4 nanopowders photocatalyst was found to be of first order. The photocatalyst could be easily removed from the reaction mixture and its recyclability with no loss of activity was possible for six times. The catalytic performance was found to decrease by 5% after run number six.

Microporous chitosan (CS) membranes were directly prepared by extraction of poly(ethylene glycol) (PEG) from CS/PEG blend membrane and were examined for iron and manganese ions removal from aqueous solutions. The different variables affecting the adsorption capacity of the membranes such as contact time, pH of the sorption medium, and initial metal ion concentration in the feed solution were investigated on a batch adsorption basis. The affinity of CS/PEG blend membrane to adsorb Fe(II) ions is higher than that of Mn(II) ions, with adsorption equilibrium achieved after 60 min for Fe(II) and Mn(II) ions. By increasing CS/PEG ratio in the blend membrane the adsorption capacity of metal ions increased. Among all parameters, pH has the most significant effect on the adsorption capacity, particularly in the range of 2.9-5.9. The increase in CS/PEG ratio was found to enhance the adsorption capacity of the membranes. The effects of initial concentration of metal ions on the extent of metal ions removal were investigated in detail. The experimental data were better fitted to Freundlich equation than Langmuir. In addition, it was found that the iron and manganese ions adsorbed on the membranes can be effectively desorbed in 0.1 mol/L HCl solution (up to 98% desorption efficiency) and the blend membranes can be reused almost without loss of the adsorption capacity for iron and manganese ions.

We developed an efficient, simple chemical reduction method to produce highly active palladium (Pd) nanoparticles in polyethylene glycol (PEG) with no other stabilizer. The as-prepared Pd/PEG catalyst demonstrated a remarkable catalytic activity toward hydrogenation of both styrene and nitrobenzene under mild conditions. The Pd-PEG catalyst could be easily removed from the reaction mixture and its recyclability with no loss of activity was possible for seven times in case of styrene and three cycles for nitrobenzene. The catalytic performance was found to depend essentially on the catalyst and target concentrations and the reaction time. The catalyst was fully characterized by a variety of techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and N 2 adsorption–desorption isotherm. The reactivity of the Pd/PEG catalyst toward hydrogenation reactions is attributed to the high degree of dispersion of Pd(0) nanoparticles in PEG with small average particle size distribution of 5 nm. Results of the synthesis and characterization of Pd/PEG catalyst and its catalytic performance for hydrogenation reactions are presented and thoroughly discussed.

Fabrication of porous silicon layers using the electrochemical technique followed by filling the nanopores with a group of conducting polymers is investigated. Our findings revealed that the deposition of polymer proceeds homogeneously inside the nanopores strating from the pore bottom and propagates into the outer surface. The polymerization process was conducted and controlled by the potentiostatic and galvanostatic modes with charactarestic, defined polymerization stages. As-formed hybrid nanocomposites were charactarized using different analytical techniques. Polypyrrole, polyaniline and polythiophene were tested in this study. By selective dissolution of porous silicon template, polymeric nanowires were obtained. The fabrication process, the electrochemical measurements and the porous silicon filling mechanism with polymer are throughly addressed and discussed (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ni–Cu–Si heterojunction was prepared by the liquid phase epitaxy (LPE) technique. Two growth solutions containing Indium (In) with Cu pieces and In with Ni pieces were employed during the fabrication process. The as-formed junction was directly characterized by different techniques including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and thin film X-ray diffraction (XRD) measurements. The current–voltage ( I – V ) characteristics of the Au/Ni/Cu/Si diode were found to be nonlinear, asymmetric, having a good rectification behavior with a very small leakage current of 0.003 μA at a reverse bias voltage of 2.0 V. The value of turn on voltage was located at 0.2 V. The magnetic properties were also evaluated at room temperature with a vibrating sample magnetometer. Systematic study of junction fabrication and characterization of such a heterosystem, comparison of the behavior of flat silicon and nanoporous silicon as substrates are presented and thoroughly discussed.

A sol–gel process followed by a calcination treatment was employed to synthesize magnetic Ni/NiO nanoparticles. The as-formed particles were characterized using XRD, TEM, UV–vis, surface area and VSM. The XRD results show that the patterns of the product synthesized using 1:1, 1:2, and 1:3 molar ratio of nickel nitrate/citric acid composed of a mixture of NiO and Ni, whereas the patterns recorded for 2:1 and 3:1 molar ratio exhibited a single NiO phase. All the prepared samples are in the form of nanoparticles with sizes locate in the range of 33 up to 118 nm for the samples prepared by different molar ratios. The photocatalytic tests were conducted for degradation of EDTA. The results show that the EDTA removal efficiency is 99.9% at 3 × 10−3 M EDTA concentration. The reaction of Ni/NiO with EDTA follows first order kinetics with respect to EDTA. The rate constants and t1/2 for Ni/NiO at 0.4 g/l catalyst/EDTA solution ratio were, respectively 460 min−1, 15.1 min.

Spinel cobalt ferrite nanowires were successfully prepared in mesoporous silica SBA-15 as a host matrix followed by slow thermal decomposition of the precursors inside the silica-based template. The formation and phase control of as-synthesized nanostructured cobalt ferrites were confirmed by X-ray diffraction (XRD) measurements at different annealing temperatures ranging from 500 to 1000 °C. The one-dimensional spinel nanostructures were identified by recording the transmission electron microscopy (TEM) images after a selective removal of the silica template in aqueous solution of NaOH. The final product was also characterized using infrared spectroscopy (FT-IR) and vibration sample magnetometer (VSM). The presence of SBA-15 lowers the formation temperature of cobalt ferrite nanowires compared to the corresponding bulk material. The nanowires annealed up to 700 °C exhibited magnetic behavior characteristic for soft magnetic materials, whereas samples annealed at temperature higher than 700 °C revealed magnetic behavior characteristic for hard magnetic materials with rectangular form and large coercive field.

Mesoporous titania containing gold nanoparticles has been found to be an efficient photocatalyst for the visible-light decontamination of Soman. This contrasts with the complete lack of visible-light activity of analogous mesoporous titania sample without containing Au and is attributed to light absorption by the gold nanoparticles surface plasmon band. The possibility that Soman degradation occurs by light-induced heating is unlikely since no variation of the temperature is observed in the irradiation. The solid photocatalysts have been prepared in a single step in which incorporation of gold and formation of titania occur in the same sol–gel process. It was observed that the molar proportion of Pluronic added to the synthesis sol as template to produce mesoporosity in the material plays an important role controlling the textural properties, surface area and pore diameter, intensity of the surface plasmon band and gold loading of the solid photocatalysts. The visible-light photocatalytic activity of mesoporous titania containing gold nanoparticles towards deadly Soman is remarkable and it constitutes an environmentally friendly system operating under ambient light at the green atmosphere without the need of corrosive or toxic chemicals.

Nanostructured iron oxide was synthesized by a thermal decomposition reaction using Fe(NO3)3·9H2O in the presence of citric acid (CA) as a template agent. The produced nanopowder was characterized by XRD, FT-IR, TEM, N2 adsorption–desorption isotherms, and thermo-analytical methods. Nanostructured iron oxide with high surface area (244 m2/g) and pore diameter distribution in the range of 1–6 nm was successfully achieved. Both the particle size and phase structure are greatly influenced by the ratio of iron precursor-to-CA, operating temperature, and the reaction time. The results show also that amorphous or weak crystalline iron oxide appears at a low preparation temperature (100 °C) and turns to crystalline phase when the temperature rises to 120 °C. Pure hematite phase was obtained at 120 °C with molar ratio 2:1 Fe salt/CA, while magnetite/maghamite phase was formed at 140 °C with molar ratio 1:2 Fe salt/CA. The as-formed nanostructured iron oxide powder was tested for catalytic oxidation of carbon monoxide (CO) using advanced quadruple mass gas analyzer system. The catalytic efficiency of the process was investigated at different operating temperatures. The results show that CO is completely oxidized to CO2 at 200 °C. The catalytic process was essentially affected by the presence of maghamite phase, crystal size and surface area of the nanostructured iron oxide. Furthermore, the magnetic properties of some selected products were briefly addressed and thoroughly discussed.

An electrochemical technique for the fabrication of intermediate nano-sized pores in silicon (50–200) nm in aqueous HF solution is reported. Attempts to achieve similar nano-sized pores in the presence of organic solvents are also presented. Mesopore formation beginning with pore sizes

Magnetite (Fe 3 O 4 ) nanowires with diameters around 25 nm and lengths up to 1.5 μm have been successfully synthesized using a simple polyethylene glycol (PEG)-assisted hydrothermal technique. Powder X-ray diffraction pattern, energy-dispersive X-ray spectroscopy, and selected-area electron diffraction measurements indicated that the as-synthesized product is pure single-phase Fe 3 O 4 with a good crystalline state. The size, morphology, and structural features of the as-prepared Fe 3 O 4 were investigated by transmission electron microscopy and scanning electron microscopy. Effects of reaction-controlling parameters such as the volume ratio of PEG to water, operating temperature, and duration of process have been investigated in detail. Vibrating sample magnetometer measurements show that Fe 3 O 4 nanowires exhibit a ferrimagnetic behavior at room temperature; a saturation magnetization of 90.94 emu/g is obtained, which is essentially higher than the reported values. A reaction mechanism for the nanowire formation is also proposed.

Nanostructured porous silicon (PS) layer is prepared in a lightly doped p-type substrate (with pores

We investigated electropolymerization of polypyrrole into porous silicon template. We used three types of porous silicon templates, i.e., porous silicon with ordered macro pores, medium-sized pores and meso pores. Polypyrrole was electropolymerized from pore bottoms to pore tops in all the porous silicon templates. After removal of the templates we obtained rod-shaped polypyrrole arrays. Changing the porous silicon templates easily controlled the size of the rod-shaped polypyrrole. We also used dendritic medium-sized pores for template, and then polypyrrole rod having a roughened surface was obtained. Here we demonstrated that the size and the surface morphology of polypyrrole rod were easily tuned using porous silicon. Keywords: Porous Silicon, Template, Electropolymerization, Polypyrrole, Rod, Tube

The formation process of ordered macropores in a prepatterned p-type silicon wafer was investigated. FE-SEM observation focusing on the early stage of the pore growth clarified the two-step process of macropore formation, whose first step was isotropic pore expansion from prepared etch pits and the second was anisotropic growth in the depth direction. Investigation using different etch-pit patterns revealed that ordered macropores with constant diameters were obtained when the spacing of etch pits was 3-8 μm, while the spacing of 2 μm resulted in the pore-wall collapse. The diameter and the wall thickness of macropores showed a tendency to decrease with decreasing the spacing of prepared etch pits, which could not be explained only from the width of the space-charge region. The resistance distribution in a silicon substrate was proposed as a parameter playing a crucial role in determination of the wall thickness.

A porous silicon rugate filter was prepared and investigated for its ability to sense ethanol vapors of different concentrations. The structure shows sensitivity to concentrations above 1% in volume up to saturation at room temperature. This sensitivity is in the form of a red shift of the characteristic peak of the filter due to capillary condensation phenomenon. Exposing the structure to saturated ethanol vapor produces partial filling of the pores with liquid. Theoretical calculations using the Bruggeman effective medium approximation and characteristic matrix method were employed to estimate the average volume fraction of ethanol molecules condensed into the pores. Electrochemical oxidation of the filter was performed. Furthermore, the oxidized structure was found to improve the durability of the filter and increase the adsorbed amount of ethanol molecules into the pores. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrodeposition of iron from acidic sulfate solutions onto porous silicon (PS) prepared from n- and p-type (1 0 0) substrates is studied by electrochemical measurements. Results from current–potential curves show that deposition of iron on p-type PS can only be achieved under illumination and cathodic polarization, whereas the deposition is found to proceed on n-type even in the dark. The measurements of the cathodic current efficiency indicate that the fraction of current used for iron deposition decreases with the applied potential due to hydrogen evolution reaction which is a competing reaction to metal deposition. Scanning electron microscopy shows that very fine iron crystallites with an average size of 40–70 nm are formed under double potential step conditions. The energy band diagrams of silicon-solution interfaces determined by electrochemical impedance measurements reveal that the iron deposition mechanism on both substrates is electron transfer from the conduction band.

Copper deposition into ordered macroporous silicon prepared in p-type substrates was investigated by immersion plating and electrochemical deposition in an aqueous solution containing Cu 2+ ions. When the sample was immersed in 0.1 M CuSO 4 solution at the open circuit potential, Cu crystallites are clearly observed at the top surface and inside the pores. The deposition of Cu oxidizes the substrate simultaneously to SiO 2 . On the other hand, the potentiostatic deposition in the dark revealed that Cu deposits preferentially at the pore bottom and propagates towards the top surface. Furthermore, when the substrate was illuminated under cathodic potential, the Cu deposition was enhanced mainly at the top-surface and around the pore walls. The different deposition behavior was compared and discussed.

The deposition of nickel (Ni) onto a porous silicon (PS) layer by immersion plating from acidic and alkaline fluoride solutions has been studied. In an immersion plating bath of simple hydrofluoric acid (HF) of pH 2 containing Ni ions, no metal deposition was observed. However, visible metallic Ni was deposited from the ammonium fluoride (NH 4 F) alkaline solution of pH 8. The different deposition behaviors are discussed on the basis of mixed potential theory, etching rate of PS and the state of Ni complex formation. The modified PS layers after the immersion plating were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Fourier transform infrared spectroscopy and scanning electron microscopy were also performed to investigate the structural changes and characterizations of PS samples after the plating process. A binary PS/Ni nanostructure without Si oxides is successfully achieved from the alkaline bath.

The effect of chloride ions (Cl − ) during the immersion plating of copper onto porous silicon (PS) from a methanol (MeOH) solution has been studied. The presence of Cl − in the Cu 2+ solution was found to slow down the rate of copper deposition, as confirmed by inductively coupled argon plasma emission spectroscopy and X-ray photoelectron spectroscopy measurements. The threshold concentration of Cl − at which the deposition of copper is very severely diminished was found to be 0.1 M. The inhibition effect is discussed on the basis of the rest potential values of PS and polarization curve measurements. They revealed that the rest potential of PS upon dipping in these solutions appears to direct the metal deposition. Current density–potential curves show that at Cl − concentrations higher than 0.1 M, the reduction of Cu ions proceeds in two steps; the reduction of Cu(II) to Cu(I) followed by the reduction of Cu(I) to Cu(0). This suggests that Cu(I) species in MeOH solution can be stable over a certain potential range and this stability of Cu(I) is responsible for the inhibition of metal deposition. Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) were also performed to investigate the structural changes and characterizations of PS samples after the plating process.

Copper deposition onto a porous silicon (PS) layer by immersion plating from organic solutions was studied using methanol (MeOH) and acetonitrile (MeCN). Copper metal was deposited at the open circuit potential onto the surface of PS from MeOH solution containing copper ions while no metal deposition was detected from MeCN solution, although both solutions contain a comparable amount of residual water. The difference in the deposition behavior is related to the difference in the rest potential of PS that is mainly attributed to the solution chemistry of copper ions in these solutions. Fourier transform infrared spectroscopy revealed that the reduction of metal ions was accompanied by the simultaneous oxidation of PS. The absence of the two peaks related to Si(0) and SiO2 in X-ray photoelectron spectroscopy measurements indicates the complete coverage of the PS surface with Cu metal from MeOH solution. Current–potential curves were measured to investigate the electrochemical behavior of the solutions. The effect of an air-oxidized PS surface on the deposition behavior was also studied. © 2001 Elsevier Science Ltd. All rights reserved.

Spinel nickel zinc ferrite nanowires were successfully prepared in mesoporous silica SBA-15 as a host matrix. The powder was annealed at a range of temperatures (500–900 °C) with heating rate 0.5 °C/min. The required NiZnFe2O4 phase was obtained at 700 °C. The specific surface area SBET data revealed that the surface area of the mesoporous silica after annealing was decreased from 821 to 90 m2/g which indicated that the spinal ferrite fills the channels of mesoporous materials. The one-dimensional spinel nanostructures were characterized by X-ray diffraction, infrared spectroscopy, vibrating sample magnetometer, and transmission electron microscopy before and after a selective removal of the silica template in aqueous solution of NaOH or HF. The presence of SBA-15 lowers the formation temperature of nickel zinc ferrite nanowires compared to the corresponding bulk material. The magnetic properties revealed a high saturation magnetization level (~43 emu/g) for the Ni–Zn nanowires at 900 °C.

Size-controlled YVO4 nanoparticles are hydrothermally synthesized from propanol solutions of Y(NO3)3 and NH4VO3 (autoclave, 150 °C, 4—24 h).

Porous silicon (PSi) is often fabricated by the electrochemical etching of silicon in a fluoride-based solution [1-4]. One of the unique properties of PSi layer is the ability to precisely tune the pore size and morphology through the variation of the silicon dopant type and level and controlling the applied anodic current and etching time. The compatibility of PSi with existing silicon processing technology adds another advantage. A wide range of materials including metals, conducting polymers, oxides, magnetic alloys and semiconductors can be deposited inside the pores of PSi templates by different techniques including; the electrochemical deposition, immersion plating and electroless deposition, sol-gel and chemical vapor deposition. Such deposition strategies would lead to various surface morphologies such as nanowires or nanorods, nanotubes, nanorings, nanodots and heterogeneous nano-macrostructures. The dimensions of as-formed hybrid structures can be controlled by regulating the shape and pore size of PSi template as well as the deposition conditions. In this work, we used PSi as a template-directing synthesis of various metallic and polymeric nano-macrostructures. Firstly, preparation of various shapes and morphologies of PSi templates are given. Examples of chemical and electrochemical deposition of metals and conducting polymers are provided. We then focus on understanding of the mechanism of Cu deposition by the immersion plating method using the XPS sputter depth profiling into PSi template as a case study and discuss the processing issues associated with its deposition inside the nanoscale pores under the open-circuit condition. Various pore diameters ranging from < 5 nm up to > 1 µm are accessible in PSi layers. Typical examples of SEM images of PSi templates, mainly ordered 5 µm macropores, 120 nm medium-sized pores and 20 nm mesopores are presented in Fig.1 [5]. Results of the synthesis and characterization of the obtained PSi-deposited materials will be presented and thoroughly discussed during the conference. Keywords: Porous silicon; electrochemical deposition; immersion plating; Cu deposition; conducting polymer References F.A. Harraz, J. Sasano, T. Sakka, Y.H. Ogata, J. Electrochem. Soc., 149 (2002) C456. F. A. Harraz, A. M. Salem, B. A. Mohamed, A. Kandil, I. A. Ibrahim. Appl. Surf. Sci., 264, (2013) 391. F. A. Harraz. Appl. Sur. Sci., 287, (2013) 203. F. A. Harraz, S. M. El-Sheikh, T. Sakka, Y. H. Ogata, Electrochim. Acta, 53, (2008) 6444. K. Fukami, F. A. Harraz, T. Yamauchi, T. Sakka, Y. H. Ogata. Electrochem. Commun., 10, (2008) 56. Figure 1

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Nanocrystalline zinc oxide thin films have been successfully prepared by electrodeposition onto copper substrates using zinc nitrate aqueous solutions at various bath temperatures (30°C-75°C). The deposition was conducted using both using chronoamperometric and chronopotentiometric techniques. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques were also performed to understand the deposition process. The effects of operating temperature, solution composition, agitation and deposition potentials on the electrochemical measurements and ZnO film characteristics were fully analysed. The findings reveal that temperature and zinc ion concentration have a strong promoting effect on ZnO film formation. Structural characterisation by X-ray diffraction indicates the formation of ZnO phase and the deposited film exhibits the wurtzite structure with crystallite size around 44 nm. Scanning electron microscopy images taken under optimum deposition conditions show smooth and compact ZnO films.

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We report a simple wet chemical method to synthesise palladium nanoparticles and test their performance as an activator for the electroless copper deposition reaction. A mixture of ethylene glycol and alkaline hydroxide ions is indispensable to initiate and catalyse the chemical reduction of palladium salt. The presence of a polyvinylpyrrolidone (PVP) in the solution mixture was also found to be essential and acted as a protective agent to isolate the nanoparticles and prevent the agglomeration. The crystallinity, size and morphology and structural features of the produced nanoparticles are investigated by powder X-ray diffraction (XRD), transmission electron microscopy (TEM). The performance of the nanoparticles as a catalyst for electroless deposition of copper on both silicon and epoxy substrates is also presented.

Copper and nickel electrodeposition into ordered macropores prepared in p-type silicon has been studied in aqueous solutions containing cupric and nickel ions, respectively. When a macroporous silicon template was cathodically polarized in 0.1 M cupric sulfate solution, copper was deposited preferentially at the pore bottom in the dark, whereas the deposition was found to proceed not only at the pore bottom but also partially on the pore wall under the back side illumination. In contrast, the deposition of nickel in 0.1 M nickel sulfate solution was not possible in the dark, while deposition occurred uniformly on the entire surface of the pore wall under the back side illumination. Dissolution of silicon templates by the alkaline etching process led to the formation of copper microrods and nickel microtubes. The deposition behavior of both metals was compared and this discrepancy was discussed.

Polypyrrole (PPy) was deposited into nanostructured porous silicon (PS) layers by the electropolymerization of the corresponding pyrrole monomer in an acetonitrile solution. The potential or current transients recorded during the polymerization process exhibit different characteristic stages: preferential nucleation of PPy at the pore bottom with a partial oxidation of PS, polymer growth inside the pores, and polymerization on the outer surface of PS. Accordingly, a ternary nanostructure of PS/SiO 2 /PPy is obtained. It is very promising that a significant increase in electrical conductivity of this PS/PPy junction is observed compared to a bare PS layer, especially in lightly doped PS. In this way, complete oxidation of the PS layer is not expected during the polymerization, and polymer deposition may even partially inhibit the PS oxidation. Furthermore, the deposited PPy film could be electrochemically driven between the oxidized (conducting) form and the reduced (insulating) form with an observable color change in the film from dark brown when oxidized to faint yellow when reduced. Results of the characterization of this heterosystem, uniformity of the PPy within the pores, and the pore-filling phenomena using different surface analytical methods are presented and thoroughly discussed.

Immersion plating of nickel (Ni) on a porous silicon (PS) layer has been investigated in concentrated ammonium fluoride and dilute hydrofluoric acid (HF) solutions containing When the PS sample was exposed to the bath containing 5 M and 50 mM at pH 8, metallic Ni was clearly observed at the open-circuit potential without using a reducing agent or any activation treatment at room temperature. However, no deposition was detected when the sample was immersed in a 0.5 wt % HF solution containing the same concentration of at pH 2. The different deposition behavior is discussed on the basis of mixed potential theory, changes in the stability of Si-H bonds of PS as indicated in the Fourier transform infrared spectra, and the different state of Ni complex formation as obtained from the UV-vis spectra. The position of the Ni redox levels in both solutions with respect to the bandedges of Si was also determined and the results revealed a nearly similar energetic situation. Results from current-potential curves showed that a slow Ni deposition from the alkaline solution occurred in the dark and different possible reaction mechanisms were proposed. They also revealed the enhancement of the deposition under illumination, indicating that the deposition mechanism is electron transfer from the conduction band. X-ray photoelectron spectroscopy detected no silicon oxides on the PS surface after being immersed in the alkaline solution, giving merit that a binary PS/Ni nanostructure without Si oxides can be successfully achieved. © 2003 The Electrochemical Society. All rights reserved.

Immersion plating of metals (Ag, Cu. Ni) onto a porous silicon (PS) layer from aqueous and nonaqueous solutions has been studied. The modified PS layers after the immersion plating were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Fourier transform infrared spectroscopy and scanning electron microscopy were also performed to investigate the structural changes and microstructure of PS samples after the plating process. In booth solutions, the deposition of metal oxidizes PS simultaneously to SiO 2 . The different deposition behaviors are discussed in terms of different rest potentials of PS in these solutions and electrode potential of each metal. Immersion plating in nonaqueous organic solutions shows that a trace of residual water affects the metal deposition. Based on the results obtained, the mechanism of metal deposition is proposed. The metal deposition proceeds by nucleation and growth via the local cell mechanism. It is also found that metal deposition proceeds very differently on Si wafer and PS surfaces. The different deposition behaviors on both surfaces are discussed.

We successfully developed a single-step detection and removal unit for Bi(III) ions based on dithizone (DZ) anchored on mesoporous TiO2 with rapid colorometric response and high selectivity for the first time. [(DZ)3-Bi] complex is easily separated and collected by mesoporous TiO2 as adsorbent and preconcentrator without any color change of the produced complex onto the surface of mesoporous TiO2 (TiO2-[(DZ)3-Bi]) at different Bi(III) concentrations. This is because highly potent mesoporous TiO2 architecture provides proficient channeling or movement of Bi(III) ions for efficient binding of metal ion, and the simultaneous excellent adsorbing nature of mesoporous TiO2 provides an extra plane for the removal of metal ions.