Mohd Yusri Abd Rahman

A simple route to vertical array of quasi-1D ZnO nanofilms on FTO surfaces: 1D-crystal growth of nanoseeds under ammonia-assisted hydrolysis process.

AbstractA simple method for the synthesis of ZnO nanofilms composed of vertical array of quasi-1D ZnO nanostructures (quasi-NRs) on the surface was demonstrated via a 1D crystal growth of the attached nanoseeds under a rapid hydrolysis process of zinc salts in the presence of ammonia at room temperature. In a typical procedure, by simply controlling the concentration of zinc acetate and ammonia in the reaction, a high density of vertically oriented nanorod-like morphology could be successfully obtained in a relatively short growth period (approximately 4 to 5 min) and at a room-temperature process. The average diameter and the length of the nanostructures are approximately 30 and 110 nm, respectively. The as-prepared quasi-NRs products were pure ZnO phase in nature without the presence of any zinc complexes as confirmed by the XRD characterisation. Room-temperature optical absorption spectroscopy exhibits the presence of two separate excitonic characters inferring that the as-prepared ZnO quasi-NRs are high-crystallinity properties in nature. The mechanism of growth for the ZnO quasi-NRs will be proposed. Due to their simplicity, the method should become a potential alternative for a rapid and cost-effective preparation of high-quality ZnO quasi-NRs nanofilms for use in photovoltaic or photocatalytics applications. PACS: 81.07.Bc; 81.16.-c; 81.07.Gf.

Seed-Mediated Liquid Phase Deposition Method for TiO2 Nanostructure Growth on ITO Substrate: Effect of Surfactant

This paper reports the study on the effect of the surfactants, cetyltrimethylammonium bromide (CTAB) and hexamethylenetetramine (HMT) on the growth of TiO2 nanostructures on ITO surface. TiO2 nanostructures were prepared using a seed-mediated liquid phase deposition (LPD) method. LPD is an electrolysis deposition of metal oxide via hydrolysis of metal-fluoro complex in the presence of boric acid at ambient temperature. In typical case, this method allows the formation of metal oxide film on the substrate surface. Since the properties strongly depend on shape at this length scale, the morphology control growth of TiO2 nanostructures is highly demanded in order to produce desired properties in application. In this work we demonstrate the growth of wire like structure of TiO2 (instead of film) on ITO surface via a seed-mediated liquid phase deposition in the present of surfactant. In typical result, TiO2 with diameter ca. 40 nm at the bottom of nanowire to ca. 10 nm at the nanowire tip can be successfully grown on the surface. The effect of surfactant and their concentration on the growth characteristics of TiO2 nanostructure will be discussed.

Effect of hexamethylenetetramine (HMT) concentration on the properties of boron doped ZnO nanotubes array films and the performance of dye-sensitized solar cell (DSSC)

This paper reports the effect of hexamethylenetetramine (HMT) concentration on the structural, morphological and optical properties of B-doped ZnO nanotubes arrays. B-doped ZnO nanotubes were employed as anode in dye-sensitized solar cells (DSSCs). The effect of these properties on the photovoltaic performance was also studied. B-doped ZnO nanotube arrays were prepared via hydrothermal technique on FTO substrate at constant concentration of zinc nitrate. The field emission scanning electron microscopy (FESEM) images indicate that the density and length of B-doped ZnO nanotubes increase with the concentration of HMT. However, the diameter decreases with the increase of HMT concentration. The JSC, VOC, FF and η of 1.48 mA cm−2, 0.38 V, 0.39 and 0.224% respectively have been obtained by the DSSC utilizing B-doped ZnO nanotube prepared at 0.06 M HMT.

Fabrication of photoelectrochemical cell using highly compact vertical array zno nanorod

Highly compact vertical array ZnO nanorods on the FTO coated glass was fabricated for photoelectrochemical cell of FTO/ZnO/electrolyte/platinum. ZnO nanorods were grown on the FTO substrate at room temperature via ammonia assisted rapid hydrolysis process technique. In typical process, ZnO nanorods were characterized by FESEM with vertical array oriented with average diameter and length of 48 nm and 218 nm, respectively. The sample was grown throughout the surface by using four cycle growth process. The photoelectrochemical cell property was studied in dark and under illumination of 100 mWcm-2 light. The cell exhibits photovoltaic effect with JSC of 0.22mAcm-2, VOC of 0.44 V, and conversion efficiency of 0.03%. Keywords: Vertical array ZnO nanorods, Photoelectrochemical solar cell

Solid state photoelectrochemical cells utilising graphite thin films counter electrode

This paper reports the use of graphite thin films as a counter electrode of a solid state photoelectrochemical cells of ITO/TiO2/PVC-LiClO4/graphite. The photoelectrochemical cells material was a screen-printed layer of titanium dioxide onto an ITO-covered glass substrate which was used as a working electrode of the device. The solid electrolyte used was PVC-LiClO4 that was prepared by solution casting technique. The graphite films which serve as a counter electrode were prepared onto glass substrate by electron beam evaporation technique at substrate temperatures variation of 25, 50, 100, 150 and 200 °C. The dependence of sheet resistance and surface morphology of the graphite films on substrate temperature were studied. The films deposited at 25 °C shows the smoothest surface morphology and the smallest grain size. Bigger grain size, rougher surface morphology of graphite film counter electrode. The current-voltage characteristics of four devices utilising the graphite counter electrode with different substrate temperature in dark as well as under illumination of 100 mWcm−2 light from a tungsten halogen lamp were recorded at room temperature and at 50 °C, respectively. It was found that the photovoltaic parameters of the device such as short-circuit current density, Jsc and open-circuit voltage, Voc increases with the decreasing average grain size of the graphite counter electrode. The device whose graphite film counter electrode was deposited onto the glass substrate at 25 °C gave the highest Jsc of 0.32 µA/cm2 and Voc of 117 mV, respectively.

Preparation and Characterization of TiO2 Nanowire - Cu2O Nanocube Composite Thin Film

Composite of TiO2 nanowire and Cu2O nanocube has been prepared. TiO2 nanowire with ~240nm in thickness and 20 nm in length were synthesized by using liquid phase deposition(LPD) method at 50°C for 4h on ITO substrate. The anatase phase of TiO2 nanowire was obtained by annealing the samples at 400°C for 1hin air. The Cu2O nanocubes were prepared by the reduction of Cu2+ions with ascorbic acid in the present of trisodium citrate and sodium dodecilsulfat (SDS) surfactant under an alkaline condition. The SDS addition was added with various concentrations namely 10 mM, 18 mM, and 26 mM during the Cu2O preparation for spin-coated onto TiO2 nanowire at 3000 rpm for 30s. An optical property of TiO2 Nanowire - Cu2O Nanocube has been characterized by UV-Vis spectroscopy.The original TiO2 nanowire has single absorption peak at 318 nm, but it was shifted to 321 nm as Cu2O/SDS addition. A new peak at 440 nm was as the Cu2O nanocube absorption spectra. The Cu2O nanocube addition to the TiO2 nanostructure film caused increase in the optical absorption of the system in the region 400 – 800 nm. We also studied the absorption properties of the hybrid system when Cu2O nanocube preparation under SDS condition. It was that found the increase in the SDS concentration has caused the optical absorption of the hybrid in this region decreased. This is believed due to the decrease of Cu2O nanocube size as the SDS concentration increase. This could be due to change in the TiO2 nanowire-Cu2O nanocube hybrid-structure. This cooperate may find use in photoelectrochemical application.

Effects of LiCF3SO3 on PVDF-HFP/MG49 (70/30) Based Blend Polymer Electrolyte

Poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP), Poly (methyl methacrylate)-grafted natural rubber (MG49) (70/30) complexed with different compositions of lithium trifluoromethane sulfonate (LiCF3SO3) based solid polymer electrolyte has been prepared using solution casting method. This work has demonstrated that conductivity values were found to depend upon the concentration of LiCF3SO3. The highest ionic conductivity was 1.97×10ˉ4 S cm-1at 25 wt. % of LiCF3SO3 at room temperature. X-ray diffraction (XRD) indicates decrease in the degree of crystallinity by increasing of salt concentration.

The Optical Properties of Ammonia Treated TiO2 Nanostructure Prepared by Liquid Phase Deposition Method

. TiO2 was known for its potential in solar cell and photocatalyst application. However the usage of anatase TiO2 in solar cell application has its own disadvantage as TiO2 spectrum was limited to ultraviolet (UV) light limiting its application. It was found that the broader optical absorption of TiO2 can be obtained by nitrogen doping. This paper report the optical properties study of ammonia treated TiO2 nanostructures with various percentage concentration of ammonia. The TiO2 nanostructures was prepared by liquid phase deposition (LPD) method using on ITO substrate and annealed at 450 °C for 1h. The TiO2 nanostructures were characterized with rod-like morphology with length and diameter of ca. 100 nm and ca. 100 nm respectively that vertically oriented on the surface. The optical properties of the samples exhibit strong band near the UV region. The optical properties drastically changed if the samples treated with ammonia, of which exhibit the present of broader absorption band in the visible region. The TiO2 treated ammonia should be find used in photoelectrochemical (PEC) solar cell application.