Abhishek Dhar

Efficient esterification of n-butanol with acetic acid catalyzed by the Brönsted acidic ionic liquids: influence of acidity

The efficiency in the catalytic performance of halogen free functionalized room-temperature Bronsted acidic ionic liquids (BAILs), having different acidities (due to the ILs containing zero, a single, and or a double –SO3H functional group), for the esterification of n-butanol with acetic acid under various reaction conditions was investigated. The synthesized BAILs have much weaker corrosiveness than that of H2SO4. The nature of both counter anion and cation as well as the presence of additional functional (–SO3H) groups influenced the behavior of the catalyst. Interestingly, the acidic character of the ILs facilitates the reaction under extremely mild conditions, with a short reaction time, and reduction in the side reactions; moreover, the liquid–liquid biphasic reaction mode leads to good yields. The physicochemical properties of these BAILs were characterized by a variety of different analytical and spectroscopic techniques, such as NMR, FT-IR, mass spectrometry, TGA, and UV-vis spectroscopy for the determination of Hammett acidity. In particular, IL-5 having the highest acidity demonstrated excellent catalytic activity for esterification. An additional advantage of BAILs is the simple procedure for the separation of product and catalyst, where the catalysts can be easily recycled without the loss of catalytic activities, making IL-5 an important alternative catalyst for a commercially viable esterification process.

Fabrication and characterization of next generation nano-structured organo-lead halide-based perovskite solar cell

AbstractGeneration of alternative source of energy is one of the talks of the present decade. In the present work, the focus has been given to produce energy from perovskite-based solar cells. For this purpose, a unique and novel nano-structured perovskite material ethyl ammonium lead chloride (C2H5NH3+PbCl3−) was prepared through a novel co-precipitation route using ethyl amine (C2H5NH2) and hydrochloric acid as the starting precursors with aqueous solution of Pb(CH3COO)23H2O. Finally acetic acid was added in the solution, and this solution was allowed to concentrate and cooled down at room temperature. Then the synthesized material was deposited over TiO2 film in order to fabricate the solar cell. Systematic study using XRD, SEM, UV, and photo conversion were conducted to properly analyze the structural, optical, and electrical properties of device. In the presence of light, this perovskite-based solar cell has shown energy conversion efficiency (η) of around 5.2% which is appreciably good. This result has depicted that this material is promising material for fabrication of highly efficient solar cells. This technology can be applied in industrial scale as substitute of the conventional energy in the future. Graphical abstractᅟ

Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

The non-ionic triblock copolymer, Pluronic® F127, has been selected to observe its interaction with ionic liquids (ILs) in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC) of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO) moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs.

An overview of engineered porous material for energy applications: a mini-review

The ordered porous materials, developed using various templating materials, have generated huge interest among the electrochemist community due to their plenty of unique properties and functionalities that can be effectively applied in optoelectronic devices. Mesoporous materials possess excellent opportunities in energy storage and energy conversion applications due to their extraordinarily high surface area and large pore size. These properties may enhance the performance of porous materials in terms of lifetime and stability, energy and power density. In this review, we have tried to club the fields of optoelectronics and mesoporous materials. Also, we have summarised the primary methods for preparing mesoporous materials using various templates and described their applications as electrodes and catalysts in fuel cells, solar fuel production, dye-sensitised solar cells, perovskite, supercapacitors and rechargeable batteries. Finally, we have highlighted the research and development challenges of mesoporous materials those need to be overcome to enhance their contribution in renewable energy applications.

One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides

Abstract Super acidic nanostructured sulfated aluminum-zirconium binary oxides in mole ratios of Zr4+: Al3+ as 2:1 (SAZ-1), 1:1 (SAZ-2), 1:2(SAZ-3) and the reference catalyst super acidic sulfated zirconia (SZ) were synthesized by a precipitation method. Firstly, the catalytic performance of these four catalysts was evaluated during the isomerization of n-hexane to 2-methyl pentane and 3-methyl pentane, n-heptane and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions (40°C and 1 atm). SAZ-1 performed the highest active and selective isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The catalytic activity of the reference catalyst SZ was the lowest among the four synthesized catalysts. TEM analysis applied to SAZ-1 and SZ indicated the presence of particle-bulks having average size of 20 nm; moreover, these materials presented an amorphous nature, having no particular surface morphology. XRD confirmed the amorphous structure of SAZ-1 and SZ as well as indicated their internal phase structure. FTIR generated ideas about different linkages and bond connectivities between atoms and groups in SAZ-1 and SZ. Ammonia-TPD of these two materials confirmed the higher super acidic nature of SAZ-1 and lower super acidic nature of SZ. Catalyst evaluation and characterization allowed to propose a reaction mechanism, elucidating a possible role of Brønsted and Lewis acid sites on the studied reaction-catalyst, being the former active sites the main factor leading to isomerization reaction. AFM and SEM pictures indicated the nature of the surface of the catalysts. Nevertheless, SEM analysis before and after the reaction displayed that catalyst morphology was modified and could influence the activity of the catalyst. The use of SAZ-1 is cost saving as well as energy saving.

Pyridinium-clubbed dicationic ionic liquid electrolytes for efficient next-generation photo harvesting

We have developed a new series of pyridinium based dicationic ionic liquids (DCILs) having excellent thermal stability and good ionic conductivity. The effectiveness of these DCIL based electrolytes in photovoltaic devices and the effect of different anions (e.g. iodine, bromide, and thiocyanate) versus the device performance are studied by cyclic voltammetry (CV), current–voltage (I–V) characteristics and electrochemical impedance spectroscopy (EIS). The electrolyte 2PrSCN based device C exhibited the highest photo conversion efficiency (PCE) of 5.23% under 1 sun (100 mW cm−2) illumination of light. We have also analyzed the influence of various anions in metal-free dye-sensitized TiO2 and the DCIL interface using the EIS technique. Device C based on 2PrSCN shows excellent long-term stability, maintaining <95% of the initial efficiency after 500 h.

Fabrication of D–π–A sensitizers based on different donors substituted with a dihydropyrrolo[3,4-c]pyrrole-1,4-dione bridge for DSSCs: influence of the CDCA co-absorbent

The effect of co-absorbance on the performance of DSSC devices with a new design of dimer sensitizers possessing a 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP) bridge and various donor groups (carbazole, diphenyl amine, indole) is reported in the present work. The co-absorbent (CDCA = chenodeoxycholic acid) was inserted into the sensitizers and the photovoltaic performance was studied. The co-absorbent had a significant effect on Jsc, Voc and the efficiency. Without incorporation of the co-absorbent, a higher efficiency of around 4.40% is exhibited (Jsc = 9.91 mA cm−2 and Voc = 0.678 V) by the R3 device, while after adding the co-absorbent, we have achieved an efficiency of around 4.44% (Jsc = 10.3 mA cm−2 and Voc = 0.693 V). Structure optimization and energy level calculations were carried out by density functional theory (DFT) with different donor substituents and DPP bridge based sensitizers. The co-absorbent and sensitizer based DSSCs were also characterised by impedance spectroscopy and incident photon to current conversion efficiency measurements.

n-Alkane isomerization by catalysis—a method of industrial importance: An overview

Abstract This review article provides an overview of the advances in the field of hydro-conversion of n-alkanes with particular stress on the promising ways to meet the requirements for improved quality of motor fuels and oils, which have been marked during the past decades. Particular attention is given to a catalyst formulation for conversion of n-alkanes to branched hydrocarbons. The particular challenge is to find an effective catalyst, which favors the isomerization of n-alkanes without too much cracking. The regulation of active sites and adsorption properties, as well as the topology of support surfaces, allows a potential predictive design of novel catalysts for conversion of n-alkanes into their branched isomers. Graphical Abstract

Synthesis and Characterization of Solid-Phase Super Acid Catalysts and Their Application for Isomerization of N-Alkanes

ABSTRACT In the present work, first, the reference catalyst super acidic nanostructured sulfated zirconia (SZ) and super acidic nanostructured aluminum chloride impregnated sulfated zirconium oxides in mole ratios of Zr4+:Al3+ as 2:1 (ACSZ-1), 1:1 (ACSZ-2), and 1:2 (ACSZ-3) were synthesized by a simple precipitation method. The catalytic performance of these four catalysts were evaluated during the isomerization of n-hexane, n-heptane, and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions. ACSZ-2 shows high activity toward isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The reference catalyst SZ was proved to be less effective compare to the other three synthesized ACSZ catalysts. Ammonia-temperature-programmed desorption of these two materials ensures that the super acidity of ACSZ-2 is higher than that of SZ. Atomic force microscopic and scanning electron microscopic pictures predict the nature of the surface of the catalysts. Transmission electron micrographic analysis indicates the presence of particle-bulks having average size 12–20 nm, presenting an amorphous nature and having no definite surface morphology of ACSZ-2. Fourier transform infrared provides an outline regarding different linkages and bond connectivities between atoms and groups in ACSZ-2 and SZ. After catalyst evaluation and characterization a probable reaction mechanism has been proposed theoretically. The reactivity and selectivity of ACSZ-2 and SZ as well as the order and activation energy of the isomerization reactions in presence of ACSZ-2 have been calculated. The use of ACSZ-2 is beneficial from the point of cost efficiency as well as its use is energy saving.

Prediction of Thermodynamic Consistency of Vapour-liquid Equilibrium of a Two-Phase System in the Presence of the Salting-in and Salting-out Effects

Abstract Salt effect on vapour–liquid equilibrium (VLE) has been a subject of intense investigation from experimental and modelling perspectives since the salting-in and salting-out effects might eliminate the possibility of azeotrope formation at saturation. Nevertheless, thermodynamic consistency evaluation of data generated from this type of studies, accounting for non-idealities of one or two of the phases involved, is mandatory. In this communication, a primary evaluation of thermodynamic consistency under a non-ideal VLE situation of data generated for an ethanol–water system with and without the addition of inorganic potassium chloride (KCl) salt is presented. The equilibrium data (T-x-y diagram) for ethanol–water system is generated under isobaric conditions, with and without 2 and 4 g/L concentration levels of KCl. The isobaric VLE data of ethanol–water system saturated with KCl concentrations are correlated by means of a modified Raoults law to predict the activity coefficient of the volatile components. Activity coefficients are evaluated using a state equation and fugacities as well. Both methodologies give identical activity coefficients, indicating that Raoults law is a simple approach to calculate these parameters. Thermodynamic consistency of VLE data with and without the addition of KCl is validated from a simple but reliable strategy that makes use of the Gibbs–Duhem plot and Murthys approach which avoids the use of enthalpy of mixing.