A Study on the Effect of Gold Nanoparticles for Dye Sensitized Solar Cell Using Hibiscus Rosa-Sinensis as Photosensitizer

Dye-sensitized solar cells (DSSC) mainly uses organic components as an alternative way of light harvesting element to replace the traditional silicon solar cells. Natural dye alternatively is being used as sensitizers to overcome the limitation of inorganic ruthenium dye which contains heavy metal. In this study, DSSC is expected to enhance its optical properties and light absorption by implementing gold (Au) nanoparticles. Various natural and organic sources can be extracted and acted as a photosensitizer to trap solar energy. Fresh Hibiscus Rosa-Sinensis flowers are one of the good candidates to give higher light absorption in DSSC. The characteristics of the dye photosensitizer will be observed under UV-Vis-NIR Spectrophotometer. The efficiency of complete DSSC will be determined by using LIV tester. An attempt to enhance light-harvesting efficiency and hence the light to current conversion efficiency by mixing Au nanoparticles TiO₂ QUOTE   paste. Au nanoparticle was selected because it can act as a medium between the dye and Ti QUOTE  O₂ to increase the electron transmission speed. The Hibiscus dye in DSSC achieved an efficiency of 0.14%. However, the efficiency reduced to 0.000178% as Au NPs was added. The effects of the addition of Au nanoparticles are discussed.&nbsp

A Study on the Effect of Gold Nanoparticles for Dye Sensitized Solar Cell Using Hibiscus Rosa-Sinensis as Photosensitizer

Dye-sensitized solar cells (DSSC) mainly uses organic components as an alternative way of light harvesting element to replace the traditional silicon solar cells. Natural dye alternatively is being used as sensitizers to overcome the limitation of inorganic ruthenium dye which contains heavy metal. In this study, DSSC is expected to enhance its optical properties and light absorption by implementing gold (Au) nanoparticles. Various natural and organic sources can be extracted and acted as a photosensitizer to trap solar energy. Fresh Hibiscus Rosa-Sinensis flowers are one of the good candidates to give higher light absorption in DSSC. The characteristics of the dye photosensitizer will be observed under UV-Vis-NIR Spectrophotometer. The efficiency of complete DSSC will be determined by using LIV tester. An attempt to enhance light-harvesting efficiency and hence the light to current conversion efficiency by mixing Au nanoparticles TiO₂ QUOTE   paste. Au nanoparticle was selected because it can act as a medium between the dye and Ti QUOTE  O₂ to increase the electron transmission speed. The Hibiscus dye in DSSC achieved an efficiency of 0.14%. However, the efficiency reduced to 0.000178% as Au NPs was added. The effects of the addition of Au nanoparticles are discussed.&nbsp

Effects of functionalized carbon nanofillers on the spectral selectivity behavior of aluminum nanocomposites for solar absorber applications

The effects of functionalized multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) on the spectral selectivity behavior of aluminum (Al) nanocomposites were investigated in this study. The attachment of the carboxylic (COOH) functional group on the surface of the carbon nanofillers was confirmed by Fourier transform infrared spectroscopy. The pristine and functionalized MWCNTs and GNPs were introduced into pure Al powder at different concentrations (5, 10, and 15 wt%) to produce Al–MWCNT–GNP and Al–MWCNTCOOH–GNPCOOH nanocomposites. The results show that the dispersion of the carbon nanofillers is better and the spectral selectivity ratios are higher for the Al–MWCNTCOOH–GNPCOOH nanocomposites compared with those for Al–MWCNT–GNP nanocomposites. In addition, the light absorption is significantly enhanced in the ultraviolet, visible, and near-infrared regions (200–2500 nm) whereas the reflectance is significantly enhanced in the near-infrared, mid-infrared, and far-infrared regions (3000–14 000 nm) for the Al–MWCNTCOOH–GNPCOOH nanocomposites. The highest spectral selectivity ratio (27.41) is attained for the Al nanocomposite with 2.5 wt% MWCNTCOOH and 2.5 wt% of GNPCOOH

Biodegradable Mulches Based on Poly(vinyl Alcohol), Kenaf Fiber, and Urea

This paper describes the preparation of poly(vinyl alcohol)/kenaf fiber (PVOH/KF) composites with entrapped urea. The major FTIR peaks of these composites could be identified. These composites are intended for agricultural applications as biodegradable mulches and could be potential carrier materials for fertilizer. The water solubility, release behavior, chemical properties, and thermal stability of the composites were evaluated. The composites lost 25% of their weight after 7 days in water. In a wet environment, urea was released from the composites through its dissolution in water, and around 57% of the urea was released from the composites in 24 h; Thermagravimetric analysis showed that these composites were stable up 150 C. These composites would be able to withstand rain and protect seedlings from the sun when applied in the field as mulches. For around three to four weeks, these biobased mulches could slowly disintegrate as the PVOH binder was gradually dissolved by moisture, releasing the kenaf fibers to serve as soil fertilizer without leaving any undegradable waste for disposal. Hence, they would not pose any risks to the land or biological systems

Preparation and Characterization of Poly(lactic Acid)-based Composite Reinforced with Oil Palm Empty Fruit Bunch Fiber and Nanosilica

The properties of poly(lactic acid) (PLA) bio-composite films reinforced with oil palm empty fruit bunch (OPEFB) fiber and nanosilica were studied in this work. The composite films were prepared via the solvent casting method. The composites were characterized via Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, field-emission scanning electron microscopy (FESEM), tensile testing, and X-ray diffraction (XRD). Ultraviolet visible spectroscopy results revealed that the PLA-based composites and neat PLA had similar light transmittances of approximately 89%. The FTIR and FESEM results showed that OPEFB fibers and nanosilica were embedded into the PLA matrix. The tensile strength of the composites with addition of nanosilica increased with an increasing fiber load content. The XRD analysis showed that the addition of organic or inorganic silica reduced the crystallinity of the composites. The water vapor permeability test results indicated that the inorganic silica decreased the diffusion rate of water molecules through the polymer film. The OPEFB-reinforced PLA blend with additional organic silica exhibited a higher thermal stability than the composites reinforced with inorganic silica

Effects of Oil Palm Empty Fruit Bunch Fiber on Electrical and Mechanical Properties of Conductive Filler Reinforced Polymer Composite

Low density polyethylene (LDPE), carbon black (CB), and oil palm empty fruit bunch (OPEFB) fiber composites were prepared by melt blending and compression molded into sheets. The effects of incorporated fibers on the electrical conductivity, thermal conductivity, tensile properties, and thermal degradation of the composites were investigated. FTIR results suggest that the OPEFB fibers interact poorly with the polymer matrix and lead to a decrease in mechanical properties. The electrical conductivity of the composites decreased with increasing OPEFB fiber content. Despite the slight decline in conductivity, the composites still were sufficiently conductive relative to applications such as sensors and electromagnetic shielding after the fiber addition. Reduction in thermal conductivity by as much as 10.9% was observed with the addition of 20% OPEFB fiber into LDPE/CB composites. The thermal stability of LDPE/CB/OPEFB fiber composites decreased with increasing fiber content because of the low thermal stability of the incorporated natural fiber

Evaluation on stability and thermophysical performances of covalently functionalized graphene nanoplatelets with xylitol and citric acid

An economical and environmentally friendly approach has been introduced to synthesize highly stable graphene nanoplatelets (GNPs) dispersions with different solvents e.g. water, ethylene glycol, methanol, ethanol, and 1-hexanol. The strategy involved with the introduction of hydroxyl groups through mild oxidation of GNPs which was then grafted with citric acid and xylitol that polymerized together, improving the solubility of GNPs. The functionalization of GNPs was proved by Fourier transform infrared (FTIR), Raman spectroscopy and high resolution-transmission electron microscope (HRTEM). Further study was carried out by using xylitol and citric acid (XC)-treated GNPs as an additive in base fluid to check their thermophysical properties. Great stability for water-, methanol-, ethanol-, 1-hexanol- and ethylene glycol-based XC-treated GNPs dispersions at 0.01 wt% was achieved, representing stable weight concentrations of 89%, 75%, 72%, 64% and 82% after 15 days, respectively. In addition, the XC-treated GNPs show remarkable enhancement in the thermal conductivity up to 34% at 60 °C. Furthermore, water-based XC-treated GNPs dispersions with different concentrations show Newtonian behaviour

Colloidal stability measurements of graphene nanoplatelets covalently functionalized with tetrahydrofurfuryl polyethylene glycol in different organic solvents

In this study, a facile, efficient, and cost-effective method was proposed for mass-production of tetrahydrofurfuryl polyethylene glycol-functionalized graphene nanoplatelets (TFPEG-treated GNPs) with improved colloidal stability in water and different organic solvents. In this method, zirconium(IV) oxychloride octahydrate was used as catalyst to covalently functionalize GNPs with TFPEG via direct esterification of carboxylic acid on the GNPs with the hydroxyl chains of TFPEG. Covalent functionalization was verified by Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. Further, the morphology of the TFPEG-treated GNPs was determined via a high-resolution transmission electron microscopy. The stability of the treated GNPs in colloidal form was examined by dispersing 0.01 wt% of the solid sample into different organic solvents namely distilled water, methanol, ethanol, ethylene glycol, and 1-hexanol. It was found that the sedimentation rate of TFPEG-treated GNPs in distilled water, methanol, ethanol, ethylene glycol, and 1-hexanol was at 11, 25, 36, 18, and 47%, respectively, recorded after 15 days. Viscosity and thermal conductivity of water-based TFPEG-treated GNP nanofluids were also measured at different concentrations (0.100, 0.075, 0.050, and 0.025 wt%). The results suggest that these nanofluids have great potential for use as working fluids in industrial heat transfer systems

Facile hydrothermal method for synthesizing nitrogen-doped graphene nanoplatelets using aqueous ammonia: dispersion, stability in solvents and thermophysical performances

A simple and green approach has been developed to synthesize nitrogen-doped graphene nanoplatelets (N-doped GNPs) for mass production with a very high stability in different solvents e.g. water, ethylene glycol, methanol, ethanol, and 1-hexanol. The strategy is based on mild oxidation of GNPs using hydrogen peroxide and doping with nitrogen using hydrothermal process. The modification of N-doped GNPs was demonstrated by FTIR, TGA, XPS, Raman spectroscopy and high resolution-transmission electron microscope (HRTEM). Further study was carried out by using N-doped GNPs as an additive to prepare different colloidal dispersions. Water-based N-doped GNPs, methanol-based N-doped GNPs, ethanol-based N-doped GNPs, ethylene-glycol based N-doped GNPs and 1-hexanol-based N-doped GNPs dispersions at 0.01 wt.% shown great colloidal stabilities, indicating 17%, 29%, 33%, 18%, and 43% sedimentations after a 15-days period, respectively. The thermophysical properties e.g., viscosity and thermal conductivity of water-based N-doped GNP nanofluids were also evaluated for different weight concentrations of 0.100, 0.075, 0.050, and 0.025 wt.%. Through this, it is found that the obtained dispersions have great potential to be used as working fluids for industrial thermal systems