A quantum chemistry study on the performance of porphyrin-based solar cell sensitisers; Zinc and anchor group position effects

In this work, ten porphyrin derivatives, including free-base zinc-metalised compounds were studied by varying the position of the carboxyl anchoring group and the alkyl substituents length on the remaining three phenyl rings with the aim of the cell efficiency investigation. Theoretical performances of the sensitisers in the dye-sensitised solar cell systems have been discussed by analysis of the optical absorption, the oxidised potential of ground and excited states, light-harvesting efficiency and electron injection efficiency. Due to lower symmetry of free-based porphyrins, they showed broader bands than zinc porphyrins. The second group sensitisers are better than the first one due to the smaller oxidation potential energy, higher open-circuit voltage and light-harvesting efficiency. The influence of long alkyl substituents on the photovoltaic parameters is not perceptible but ortho and meta positions of anchoring group modify the solar cell performance. Finally, some correlations between the quantum reactivity indices and photovoltaic parameters have obtained and discussed.     

Simply synthesized TiO_2 nanorods as an effective scattering layer for quantum dot sensitized solar cells

TiO2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots （QDs） by successive ionic layer adsorption and reaction （SILAR） and integrated as a photoanode in quantum dot sensitized solar cells （QDSCs）. Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% （Voc = 497 mV, Jsc = 11.32 mA/cm2, FF = 0.54）, in optimized structures. High efficiency can he obtained just by tuning the photoanode structure without further treatments, which will make this system a promising nanostructure for efficient quantum dot sensitized solar cells.     

Synthesis of nickel metal nanoparticles via a chemical reduction of nickel ammine and alkylamine complexes by hydrazine

Nickel nanoparticles were prepared from their coordination compounds, such as [Ni(NH₃)₆]Cl₂, [Ni(N₂H₄)₂Cl₂], [Ni(HNEt₂)₆]Cl₂, and [Ni(H₂NBu)₆]Cl₂ in aqueous solution by chemical reduction. The reaction of nickel ammine and alkylamine complexes with hydrazine monohydrate as a reducing agent was carried out at 90 °C and pH = 10–12. Depending on the influencing parameters such as oxidizing agent, pH, and temperature, the hydrazine reaction can be carried out in different pathways. The chemical reduction method is a simple procedure and also is the best one in the controlling of composition, size, and shape of Ni powder. The reduction of nickel complexes into the metallic Ni powder occurs via the dissociation of complexes and reduction by hydrazine in alkaline solution. Therefore, complexing agents have the most effect on the reduction reaction. The results show that, when the ligands in complexes were changed from ammine to diethylamine and butylamine, respectively, the crystalline size and morphology of nickel metal nanoparticles are changed. The chemical reduction of nickel complexes into metallic nickel can be accompanied with a change in the crystalline system. The pure nickel crystalline has a face-centered cubic structure. The nickel nanoparticles were characterized using IR spectroscopy, X-ray powder diffraction, scanning electron microscopy and vibrating sample magnetometer analyses.     

Ordered mesoporous SBA‐15 functionalized with yttrium(III) and cerium(III) complexes: Towards active heterogeneous catalysts for oxidation of sulfides and preparation of 5‐substituted 1H‐tetrazoles

Mesoporous SBA‐15 was synthesized and modified with 3‐chloropropyltrimethoxysilane and then used in immobilization of creatinine groups, which were employed to introduce Y³⁺ and Ce³⁺ to give rise to two novel yttrium and cerium catalysts: SBA‐15@Creatinine@M (M = Y and Ce). The structures of the SBA‐15@Creatinine@M catalysts were determined using various techniques. These catalysts offered outstanding catalytic performances in the oxidation of sulfides to sulfoxides and in the preparation of 5‐substituted 1H‐tetrazoles. An important characteristic of the SBA‐15@Creatinine@M catalysts is that they are very stable without a considerable decrease in their catalytic performance lasting seven cycles.     

Synchronization of different-order chaotic systems: Adaptive active vs. optimal control

In this paper, an adaptive algorithm is proposed for synchronization of chaotic systems with different orders. A modular adaptive control strategy is applied to make states of the slave system track those of the master, despite the unknown parameters. One of the most advantages of the modularity approach, which is applied for the first time in chaos synchronization, is its flexibility in choosing identification and control modules and designing them completely independently. In this paper, a modified recursive least square algorithm is used to identify the unknown parameters of the slave system, and the control module is designed by means of two different algorithms. First it is designed based on active control method, and then, in order to synchronize with a lower energy, we design an optimal controller. The two methods are applied on a practical case study, and the results are compared. Two different dimensional neuron models, the HR neuron model and the cable model of cylindrical cell, are considered as the master and slave systems, respectively. Simulation results confirm the effectiveness of the proposed method.     

Fe3O4 nanoparticles: As an efficient,green and magnetically reusable catalyst for the one-pot synthesis of 1,8-dioxo-decahydroacridine derivatives under solvent-free conditions

An efficient and environmentally friendly method for the one-pot synthesis of 1,8-dioxo-decahydroacridines has been developed in the presence of Fe₃O₄ nanoparticles. The multicomponent reactions of aldehydes, dimedone and amines were carried out under solvent-free conditions to obtain some 1,8-dioxo-9-aryl-10-aryl-decahydroacridine derivatives. The present approach provides several advantages including high yields, short reaction times, little catalyst loading and facile catalyst separation.     

Development of cloud point extraction using pH-sensitive hydrogel for preconcentration and determination of malachite green

A novel and sensitive cloud point extraction procedure using pH-sensitive hydrogel was developed for preconcentration and spectrophotometric determination of trace amounts of malachite green (MG). In this extraction method, appropriate amounts of poly(styrene-alt-maleic acid), as a pH-sensitive hydrogel, and HCl were added respectively into the aqueous sample so a cloudy solution was formed. The cloudy phase consists of hydrogel particles distributed entirely into the aqueous phase. Organic or inorganic compounds having the potential to interact with polymer particles (chemical interaction or physical adsorption) could be extracted to cloudy phase. After centrifuging, these particles of hydrogel were sedimented in the bottom of sample tube. The sedimented hydrogel-rich phase was diluted with acetonitrile and its absorbance was measured at 617 nm (λ_max of malachite green in hydrogel). Central composite design and response surface method were applied to design the experiments and optimize the experimental parameters such as, concentration of hydrogel and HCl, extraction time and salting out effect. Under the optimum conditions, the linear range was 1 × 10⁻⁸-5 × 10⁻⁷ mol L⁻¹ malachite green with a correlation coefficient of 0.992. The limit of detection (S/N = 3) was 4.1 × 10⁻⁹ mol L⁻¹. Relative standard deviation (RSD) for 7 replicate determinations of 10⁻⁷ mol L⁻¹ malachite green was 3.03%. In this work, the concentration factor of 20 was reached. Also the improvement factor of the proposed method was 23. The advantages of this method are simplicity of operation, rapidity and low cost.     

Aphron applications — A review of recent and current research

Colloidal aphrons are multi-layered stable bubbles (CGAs) or droplets (CLAs), surrounded by a thin surfactant film. The small size of the aphrons creates a system with a high interfacial area which can be pumped like water without collapsing. The high stability of colloidal aphrons due to a thin soapy shell surrounding the core, and high interfacial area make them of interest in many processes such as mineral processing, protein recovery, drilling fluids, separation of organic dyes from waste water, predispersed solvent extraction of dilute streams, clarification and purification of suspensions, soil remediation, material synthesis and immobilization of enzymes. This article aims to provide a comprehensive database in generation, characterization and applications of colloidal gas and liquid aphrons from more than 140 published works so far. The article also reports scale up, industrial applications, technical limitation regarding aphrons application and important future research scopes.