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A hybrid photoanode material consisting of reduced graphene oxide–anatase titanium dioxide (rGO–anatase TiO2) nano-composite particles was produced by mixing an rGO solution into a TiO2 solution. The hybrid particles were then electrophoretically deposited (EPD) onto a fluorine-doped tin oxide (F:SnO2) coated (FTO) glass substrate to form the novel photoanode structure for a dye-sensitized solar cell (DSSC). Incorporation of graphene materials (i.e., the rGO flakes) into the hybrid photoanode increases the dye absorption ability, light harvesting and eventually the photocurrent-density (j). At the optimal proportion of rGO, the solar cell showed a short-circuit current density $$ \left( {j_{\text{SC}} } \right) $$ of 18.37 mA cm−2, an open-circuit voltage $$ \left( {V_{\text{OC}} } \right) $$ of 0.61 V, and a fill-factor (FF) of 52.1% with a power conversion efficiency (PCE) of 6.52%. The hybrid photoelectrode produced by electrophoretic deposition of the rGO-modified TiO2 solution shows excellent photoelectrochemical properties.

The novel perovskite oxide series of Sm1-xZrxFe1-yMgyO3 (x,y = 0.5, 0.7, 0.9) were synthesized by solid state reaction method. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and conductivity analysis were carried out. XRD patterns of sintered materials revealed the shifted Bragg reflection to higher angle for the higher content of Zr and Mg. This is related to the ionic size of the dopant elements. Rietveld refinement showed that all compounds crystallized in cubic space group of Fm-3m. SEM images showed that the grains were well defined with highly dense surfaces makes it potential as an electrolyte material in solid oxide fuel cells (SOFCs) or gases sensors. Impedance spectroscopy at 550-800 °C shows that conductivity is higher at higher temperature. Sm0.5Zr0.5Fe0.5Mg0.5O3 shows the highest conductivity of 5.451 × 10-3 S cm-1 at 800 °C. It was observed that 50% molar ratio of Mg and Zr doping performed highest conductivity.

We have computationally designed and characterized a series of new organic D−π−A architected dyes that have originated from cyanidin, which is vastly available in nature, for effective sensitization of DSSCs with absorption spectra extending up to near infrared region. Cyanidin acts as the donor group while cyanoacrylic acid and thieno [3, 2-b] thiophene are employed as the acceptor and π-spacer, respectively. Sensitization performance, depending on the substituted position of the π-spacer-acceptor (π-A) combination on cyanidin molecule, is examined by the results of density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. The calculated data of free energy change driving force ( Δ G inject ), electron regeneration driving force ( Δ G regen ), open circuit potential eV OC and light harvesting efficiency (LHE) suggest two preferred substitutions of π-A combination to cyanidin molecule that leads to an efficient DSSC. At LUMO the designed sensitizers have denser electron cloud towards acceptor group that leads to an efficient electron injection process. All π-A substitutions resulted a broader absorption spectrum with a redshift up to 2500 nm which is a significant improvement compared to the vast majority of reported sensitizers.

Nanotechnology is utilized well in the development and improvement of the performance in Solid Oxide Fuel Cells (SOFCs). The high operating temperature of SOFCs (700–900 °C) has resulted in serious demerits regarding their overall performance and durability. Therefore, the operating temperature has been reduced to an intermediate temperature range of approximately 400–700 °C which improved performance and, subsequently, commercialized SOFCs as portable power sources. However, at reduced temperature, challenges such as an increase in internal resistance of the fuel cell components arise. Although, this may not be as serious as problems encountered at high temperature, it still significantly affects the performance of SOFCs. This review paper addresses the work of researchers in the application of nanotechnology in fabricating SOFCs through distinct methods. These methods have successfully omitted or at least reduced the internal resistance and showed considerable improvement in power density of the SOFCs at reduced temperatures.

New layered perovskite oxides with samarium (Sm+3) rare earth doped layered perovskite materials were synthesized and characterised by using X-ray diffraction, scanning electron microscopy (SEM), particle size measurements and thermogravimetric analysis (TGA). Sm0.5Ba0.5MnO3-δ and SmBMn2O5+δ, were synthesized by conventional solid state reaction method. Rietveld analysis of XRD data shows that all materials crystallize in the orthorhombic symmetry in the Pmmm space group. SEM images show porous structures which should be suitable as electrode materials for solid oxide fuel cells (SOFCs). TGA results indicate the mass loss of 0.022% for SmBMn2O5+δ. Density calculation shows the materials have about 85% relative density.

Cyanidin is widely considered as a potential natural sensitizer in dye-sensitized solar cells due to its promising electron-donating and electron-accepting abilities and cheap availability. We consider modifications of cyanidin structure in order to obtain broader UV-Vis absorption and hence to achieve better performance in DSSC. The modified molecule consists of cyanidin and the benzothiadiazolylbenzoic acid group, where the benzothiadiazolylbenzoic acid group is attached to the cyanidin molecule by replacing one hydroxyl group. The resulting structure was then computationally simulated by using the Spartan’10 software package. The molecular geometries, electronic structures, absorption spectra, and electron injections of the newly designed organic sensitizer were investigated in this work through density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations using the Gaussian’09W software package. Furthermore, TDDFT computational calculations were performed on cyanadin and benzothiadiazolylbenzoic acid separately, as reference. The computational studies on the new sensitizer have shown a reduced HOMO-LUMO gap; bathochromic and hyperchromic shifts of absorption spectra range up to near-infrared region revealing its enhanced ability to sensitize DSSCs.

Natural dye sensitizers from Ixora coccinea (anthocyanin) and Bougainvillea glabra (betalain) flowers were prepared in five different ratios of ethanol to water (0, 30, 50, 70, and 90 % ethanol), and the effect of dye aggregation toward dye sensitized solar cell (DSSC) performance was evaluated. As the concentration of ethanol increases, the tendency of dye molecules to aggregate increased in Ixora dye extracts while no definite trend was observed in Bougainvillea dye extracts. The best DSSC performances of Ixora and Bougainvillea dyes exhibited by extracts in 70 % ethanol and 0 % ethanol are 0.58 ± 0.02 and 0.25 ± 0.02 %, respectively. Both high conversion efficiencies were ascribed to high electron density and low charge transfer resistance. From this study, it was revealed that the performances of DSSC could be affected by the formulation of dye aggregation on the TiO2 surface.

With the rapid increase in the cumulative installations around the world, solar PV technology has started playing a major role in the global clean energy scenario. One of the major challenges for the large scale integration of solar energy with the power grids is its intermittent nature. In this paper, temporal variations in the power output of six different solar PV technologies are quantified and modeled. The solar cells considered are single crystalline, poly crystalline, micro crystalline amorphous silicon, copper Indium Selenium (CIS) and hetero-junction with intrinsic thin layer (HIT). Three years of performance data from a 1.2 MW experimental solar PV farm in Brunei Darussalam were used for the modeling. It was found that the variations in the PV output follow the Cauchy's probability distribution. Ramping down behaviour of the solar panel was critically analyzed and expected ramp downs at 95% confidence level are presented. HIT modules showed the highest ramp rate among the panels, whereas CIS showed the lowest fluctuations.

In this paper, WRF-Chem model response to horizontal resolution has been presented in simulating tropospheric ozone distribution during an intense biomass burning across Southeast Asia. Model resolution is varied between 100 km and 20 km. Enhanced fire emissions were also considered in the 20 km resolution simulation. Evaluations were made against observed meteorology such as temperature, relative humidity, wind speed and direction. Spatio-temporal distribution of ozone precursors such as NO2 and CO at the surface retrieved from OMI and MOPITT instruments respectively, were compared against model outputs. Ozonesonde datasets for ozone profile from SHADOZ campaign at Watukosek-Java, Hanoi and Kuala Lumpur were used in evaluating simulated results. All the model simulations adequately represented the observed meteorology. Except in Watukosek-Java where ozone levels were overrepresented, the levels in other locations such as Kuala Lumpur and Hanoi were captured adequately. For model simulations using low-resolution, high-resolution and high-resolution with enhanced fire emissions in Hanoi, Kuala Lumpur and Watukosek-Java region, normalized bias factors are around -0.06, 0.14 and 0.22; 0.01, 0.28 and 0.18, and; 1.20, 3.36 and 3.21, respectively. Normalized root mean square error obtained is as low as 0.09 in Hanoi, and as high as 1.02 in Watukosek-Java region.

An improvement in the efficiency of Ixora ( Ixora sp. (Rubiaceae)) floral dye sensitized solar cells (DSSCs) has been achieved by diminishing the pigment’s interactions. Liquid column chromatography (LCC) separated the dye components, namely aurone, pelargonidin, and derivatives of cyanidin & malvidin, showed improved photovoltaic performance when compared to cells sensitized by the original dye extract of Ixora. The LCC separated dye components were analyzed using UV–Vis, fluorescence and Fourier transform infrared (FTIR) spectroscopic studies. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and band gaps of the dyes were investigated. The DSSC prepared with the LCC separated dye showed energy conversion efficiencies (ECEs) ranging from 0.203% to 0.951%, whereas the original Ixora dye sensitized cell showed an ECE of 0.381%. Transient photovoltage (TPV) measurements and electrochemical impedance spectroscopy (EIS) were used to elucidate the photovoltaic parameters.

This paper describes a double layered co-sensitization in dye sensitized solar cells (DSSCs) by using natural pigments from Ixora flower (Ixora sp. (Rubiaceae)) and the outer dark purple skin of ‘Kembayau’ (Canarium odontophyllum) fruit. UV–vis absorption data revealed that both dyes were anthocyanins. Co-sensitization was done by first adsorbing the dye from C. odontophyllum into TiO2 electrode by dipping, and then by removing adsorbed dye of the top layer of TiO2 using a de-sorption solution before the Ixora sp. dye was allowed to adsorb. Power conversion efficiency of the co-sensitized solar cell was 1.55%. The conversion efficiencies of DSSCs sensitized with Ixora sp. , C. odontophyllum and the mixture of both dyes (1:1) were 0.96%, 0.59% and 1.13% respectively. The superior conversion efficiency achieved by layered co-sensitization is attributed to the high adsorption capacities of Ixora sp. and C. odontophyllum, and the homogeneous monolayer adsorption of Ixora sp. as revealed by Freundlich and Langmuir adsorption isotherms.

The active constituents of Canarium odontophyllum (COP) were investigated experimentally and theoretically for dye sensitized solar cell (DSSC) application. Three main flavonoid pigments (cyanidin, pelargonidin and maritimein) were detected in COP showing photo-energy conversion efficiencies of 1.43%, 0.87% and 0.60%, respectively. The molecular geometries, electronic structures, optical absorption spectra and proton affinity of these molecules were investigated with DFT/TDDFT. All three molecules displayed π→π * transition dominant in HOMO→LUMO transition. The anchoring groups onto TiO 2 surface were deduced from combined experimental and calculated data. All the constituents of COP are potential sensitizers for DSSC.

We report results of computational study of a newly designed cyanidin based molecular structure, P02, as efficient sensitizers for dye sensitized solar cells (DSSCs). To design this P02, widely used promising natural dye sensitizer cyanidin [1] is combined with α-cyanocinnamic acid and the resultant structure is computationally simulated by using SPARTAN’10 software package [2].The moleculer geometries, electronic structures, absorption spectra and deprotonation enengies of newely designed organic sensitizer are investigated through density functional theory(DFT) and time-dependent density functional theory(TDDFT) approach using GAUSSIAN’09W software package [3]. Furthermore DFT and TDDFT computational calculations are performed on cyanadin too, as reference. The solvation effect in ethanol are included in all calculations.The computational studies on the new dye have shown broadening of the absorption spectra in visible region with significant shifting towards a longer wavelength compared to the cyanidin. Our computational study results indicated that the new dye P02 should exhibit better performance as a sensitizer due to its improved optical properties.

Possibility of use of dye extract from skin samples of a seasonal, indigenous fruit from Borneo, namely Canarium odontophyllum, in dye sensitized solar cells (DSSCs) are explored. Three main groups of flavonoid pigments are detected and these pigments exhibit different UV-vis absorption properties, and hence showing different light harvesting capabilities. When applied in DSSCs. The detected pigment constituents of the extract consist of aurone (maritimein), anthocyanidin (pelargonidin) and anthocyanidin (cyanidin derivatives). When tested in DSSC, the highest conversion efficiency of 1.43% is exhibited by cyanidin derivatives, and this is followed by conversion efficiencies of 0.51% and 0.79% for aurone and pelargonidin, respectively. It is shown that individual pigments, like cyanidin derivatives and pelargonidin, exhibit higher power conversion efficiency when compared to that of C.odontophyllum skin pigment mixture (with a conversion efficiency of only 0.68%). The results indicate a possibility of masking effects of the pigments when used as a mixture. The acidification of C.odontophyllum skin pigments with concentrated hydrochloric acid improves the conversion efficiency of the mixture from 0.68% to 0.99%. The discussion in this paper will draw data and observations from the variation in absorption and adsorption properties, the HOMO-LUMO levels, the energy band gaps and the functional group compositions of the detected flavonoids.

We have studied the performance of dye sensitized solar cells sensitized with pigments extracted from the fruit sheath of Nephelium lappaceum (F: Sapindaceae). The pH of the pigment solution used for impregnation was controlled by adding concentrated HCl (50:0.2 v/v). The UV-Vis spectroscopic results revealed that the extract consists of the pigment of Anthocyanin, with an additional absorption peak appearing around 540nm at a lower pH of the pigment solution. Also the band gap of the pigment was reduced by 1eV at low pH conditions. The solar cells fabricated with pigment extracted from the fruit sheath of Nephelium lappaceum showed photo-response with the conversion efficiency of 0.26%, with an open-circuit voltage (VOC) of 453mV, short-circuit current density (ISC) of 1.17mA cm � 2 , and fill factor (ff) of 0.48. The conversion efficiency was significantly enhanced when pH of the pigment solution was lowered by adding concentrated HCl. The conversion efficiency of the dye sensitized solar cells (DSSCs) sensitized after HCl treatment of the pigment was increased to 0.56%, with an open-circuit voltage (VOC )o f 404mV, short-circuit current density (ISC) of 2.71mA cm � 2 , and fill factor (ff) of 0.35. The HOMO level of the pigment at low pH was shown to be shifted towards more positive values with respect to vacuum level, giving rise to an enhanced DSSC efficiency. The overall efficiency enhancement of the low pH pigment was due to the combined effect of increased UV-Vis absorption and efficient adsorption of dye molecules onto the TiO2 semiconductor surface. [DOI: 10.1115/1.4023877]

La0.75Sr0.25Mn0.5Cr0.2Ti0.3O3 has been synthesized in solid state reaction method and tested as a potential anode material for solid oxide fuel cells. Rietveld refinement of X-ray powder diffraction data of the composition using Fullprof software shows that the materials crystallize in the rhombohedral symmetry in the R-3C space group. The cell parameters are: a = b = 5.5143 (4) A, c = 13.452(1) A, α = β = 90°, δ = 120°. Addition of titanium to the B-site of La0.75Sr0.25Mn0.5Cr0.2Ti0.3O3-δ yields a total conductivity of 1.96 Scm-1 in air at 800 °C with activation energy of 1.02 eV.