Wan Zurina Samad

Preparation and characterization of HypoGel-supported Pd nanocatalysts for Suzuki reaction under mild conditions

Abstract A new heterogeneous catalyst composed of Pd nanoparticles immobilized within a HypoGel resin has been prepared in the absence of any ligands using an extensive cross-linking method. This newly developed nanocatalyst was characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy and inductively coupled plasma-mass spectrometer (ICP-MS) techniques. TEM and XRD results revealed that the Pd nanoparticles were well dispersed with diameters in the range of 4–12 nm, and an average size of about 8 nm. The cross-linked Pd catalyst demonstrated excellent catalytic activity towards the synthesis of a series of biaryl compounds by the reaction of various aryl halides (e.g., bromides andiodides) with phenylboronic acid in the presence of tetrabutylammonium bromide. ICP-MS analysis indicated that there was only 0.25% weight loss of Pd (0.55 ± 0.02 ppm) from the supported catalyst after the first cycle reaction. Furthermore, the catalyst showed excellent reusability (up to five uses) with consistently high levels of catalytic activity following its recovery by filtration.

Transparent Conductive Electrode of Fluorine Doped Tin Oxide Prepared by Inkjet Printing Technique

Fluorine doped tin oxide (FTO) thin films have been developed as alternatives to ITO for thin film transparent electrode applications. In this works, the FTO thin films were deposited using inkjet printing technique since the technique is a promising deposition method to fabricate low-cost devices. The FTO precursor was prepared by reacting SnCl4•5H2O and NH4F at 60oC in a sealed container. The thin films were deposited on glass substrates at 40oC with variations of printing layers. The optical and electrical properties of the films were affected by the number of printed layers. It was observed the four layers film has the optimum optical transmittance and sheet resistance which were 96 %T and 16.4 Ω/□ respectively.

Preparation Nanostructure Thin Films of Fluorine Doped Tin Oxide by Inkjet Printing Technique

The paper reports fluorine doped tin oxide (FTO) thin films deposited using inkjet printing technique. The FTO ink was synthesized by common mixture method between precursor tin chloride pentahydrate (SnCl4⋅5H2O) with ammonium fluoride (NH4F) as a dopant agent. The thin films were deposited on glass substrates using a piezoelectric inkjet printer with variations of deposition temperature. Morphology analysis using TEM and AFM showed that variation of the deposition temperature may affect of the nanostructure grains size and surface morphology of the thin films. Hence, the performance thin films in term of optical transmittance and sheet resistivity were found dependence on the deposition temperatures. The film deposited at 40° C has optical transmittance of 91% and sheet resistances of 16 Ω/▭.

Transparent conducting thin films of fluoro doped tin oxide (FTO) deposited using inkjet printing technique

FTO thin films were successfully prepared by inkjet printing technique. FTO precursor was prepared by reacting SnCl<inf>4</inf>.5H<inf>2</inf>O and NH<inf>4</inf>F at 60°C in a sealed container. The number of layers was set up from two to five layers on the glass substrate and was deposited at room temperature around 25 to 27° C, 40° C and 60° C to determine the optimum properties for thin films performance. Morphology analysis study using VP-SEM shows the existence of fine grains with the size ranging 20 to 30 nm and the existence of crystal shape with the increases of deposition temperature. Fluorine concentration in the thin films determined from XPS analysis shows the ratio of[F]/[Sn] at 0.02 with the Sn d<inf>5/2</inf> Sn 4+, O<inf>1s</inf> as O^2-, and F1s as Sn-F bond peaks at binding energy 486.6 eV, 530.5 eV and 684.4 eV. The optical transmittance analysis showed the deposition temperature improved the optical transmittance; 60% T at ambient to 80% T at 60° C. The optimum optical transmittance was 91% T for the thin film deposited at 40° C. The sheet resistances were 16 Ω/□, 21 Ω/□ 23 Ω/□ for the thin film deposited at 40° C, ambient temperature and 60° C.

Controlled Release Electrochemical Synthesis and Cytotoxicity Study of Copper(II) Nanoparticles in Copper(II) Decanoate Complex

In the present study, a controlled release electrochemical (CRE) technique based on the controlled release of Cu2+ ion from Cu anode in the presence of decanoic acid (HDe) has been used to synthesize Cu(II) decanoate (CuDe2) complex. The effect of applied voltages (1–10V) and electrolyte concentrations (0.1–2.0M CH3COONH4) during the electrolysis on the nanoparticles obtained was studied using TEM. The results reveal that small-sized nanoparticles (2±1nm) were obtained by using lowest applied voltage and CH3COONH4 concentration (1V and 0.1M, respectively). The smallest nanoparticle obtained was then used in the cytotoxicity study against A549 and HeLa cells. The synthesized complex gives moderate cytotoxic effect on the selected cells (IC50=15.85μM and 20.89μM, respectively) and low cytotoxic effect on normal cells (IMR90). Apoptosis is the mode of cell death based on the apoptosis assay that has been conducted.

Effect of Applied Voltage on Slow-Release of Cu(II) Ions on the Synthesis of Copper(II) Stearate Complex by Electrochemical Technique

ion from electrochemical oxidation of a Cu anode in the presence of stearic acid (HSt) and an aqueous solution of ammonium acetate (CH 3 COONH 4 ) (0.1 mol L-1) as supporting electrolyte has been used to synthesize Cu(II) stearate (Cu(II)St) complex. Different values of applied voltages (1, 5 and 10 V) were used during the synthesis to study the effect of applied voltage on the particle size of the Cu nanoparticles and morphology of the synthesized Cu(II)St complex. By using 1 V of applied voltage, small Cu nanoparticle was produced with an average particle size of 2.49 ± 0.82 nm, followed by 5 V (3.61 ± 1.18 nm) and 10 V (6.64 ± 2.72 nm). Another advantage of using 1 V of the applied voltage is the formation of well-shaped petal-like structures of the Cu(II)St complex compared to the synthesis using 5 V and 10 V which inhibit the formation of well-shaped petal-like structure. This proves that the slow-release electrochemical synthesis using lower value of applied voltage has successfully resulted in the formation of small size Cu nanoparticles.

Carbon Dioxide Adsorption and Desorption Study Using Bimetallic Calcium Oxide Impregnated on Iron (III) Oxide

Bimetal adsorbent system of calcium oxide impregnated on iron (III) oxide were evaluated as a potential source of basic sites for CO2 capture. The adsorbents were prepared by impregnation method were calcined at 200 until 600 °C. Several characterizations were carried out using XRD, BET and CO2-TPD analysis. The CaO loading increased the basicity of the adsorbent significantly enhance the CO2 chemisorption. Furthermore, it drastically reduced the desorption temperature to 310-490 °C, which is important in chemisorption aspect. The CaO/Fe2O3200 which calcined at 200 °C was found to be most efficient. The CO2 chemisorption (81.29 mg CO2/g adsorbent) was contributed most compared to physisorption (4.64 mg CO2/g adsorbent).

Effect of Ruthenium Metal Precursors Supported on Bentonite in Hydrogenolysis Glycerol

Various ruthenium precursors (Ru= RuCl3, Ru2 = Ru(acac)3, Ru3 = Ru3(CO)12) supported on bentonite were prepared by conventional impregnation method. Their catalytic performances were evaluated in the hydrogenolysis of glycerol using autoclave Parr reactor under mild reaction conditions of 150°C, hydrogen pressure 30 bar for 7 hours. Among the studied catalyst, 5% Ru/bentonite catalyst prepared from Ru and Ru3 precursor exhibited higher activity which are 79.6% and 72.5% respectively. In contrast, Ru2/bentonite prepared from Ru(acac)3 precusor gave lowest activity (41.8%). In term of selectivity to 1,2-propanediol, Ru2 and Ru3 precusor gave higher selectivity (67.0% and 66.9%) compared to Ru precursor (50.6%). These results indicated that metal precursor plays an important role on activity and selectivity of the catalyst in hydrogenolysis reaction. The catalysts were characterized by XRD, XPS, BET, FESEM-EDX and TEM, and the reasons for the high performances of the catalyst were also discussed.

Effect of metals compatibility on fluorine-doped tin oxide catalyst for glycerol conversion to 1,2-propanediol

The effect of metals on support material fluorine-doped tin oxide (FTO), were studied. A series of metals such as ruthenium (Ru), osmium (Os), palladium (Pd), and copper (Cu) on FTO support were prepared by a simple wet mixture method, and attempted as a heterogeneous catalyst to enhance the hydrogenolysis of glycerol converted to 1,2-propanediol (1,2-PDO). The physicochemical properties of the catalysts were characterized by XRD, XPS, BET, FESEM, TEM, TPR, and TPD techniques. In particular, the catalyst of Ru-FTO was recorded as a good catalyst with an optimum glycerol conversion of 100% and 1,2-PDO selectivity of 94% respectively. It was suggesting that the acid an basic properties of the catalyst could achieved the C-O and C-H bond dissociation by formation of different intermediates of acetol and acetaldehyde to become 1,2-PDO. Despite that, some reaction parameters were evaluated and optimized reaction condition were established

Influence of the calcination temperature on the catalytic properties of Os/bentonite for glycerol hydrogenolysis

Selective catalytic hydrogenolysis of glycerol on Os/bentonite catalyst represents a low cost and green route for 1,2-propanediol which is major commonity chemical used in the production of antifreeze functional fluids, paints and humectants. The experimental results combined with the characterization studies using TPR, FESEM-EDX and XPS techiniques revealed that the optimum calcination temperature was 300 °C with glycerol conversion obtained was 80.7%. This might be due to the presense of Os metal species as a active site with binding energy (BE) of Os 4f at 51.2 eV in XPS analysis. TPR profile also shows two obvious peak at reduction temperature of 95 °C and 140 °C represent for Os3+ and Os4+ species respectively. The presence of Os3+ and Os4+ species were also confirmed by XPS analysis.