Optoelectronic and thermoelectric properties of novel stable lead-free cubic double perovskites A2NaIO6 (A = Ca, Sr) for renewable energy applications.

Over the past decade, perovskites have received considerable attention because of their record power conversion efficiency (25.7%) in solar cells. These materials have also received recent research interest in thermoelectrics, most likely due to their high carrier mobility, large power factor, and ultralow thermal conductivity. Therefore, in the present work, we have examined the optoelectronic and thermoelectric properties of A2NaIO6 (A = Ca, Sr) double perovskites using first-principles calculations. Stability has been confirmed using reliable and accurate descriptors of formation energy and phonon calculations. The optimized lattice constant and volume show an increasing tendency with changing A site cation (Ca → Sr). The computed band structures depict the semiconducting nature with direct band gap values of 2.64 eV (Ca2NaIO6) and 2.48 eV (Sr2NaIO6). The absorption was found to start in the visible range where the reflectivity was less than 10%. Moreover, the high Seebeck coefficient, large electrical conductivity, and fairly low thermal conductivity result in ZT values of 0.724 for Ca2NaIO6 and 0.686 for Sr2NaIO6 at 1000 K. With their optimum band gap, excellent light absorption capacity, and high ZT values, A2NaIO6 emerge as promising candidates for optoelectronic and thermoelectric applications.

Cu-doped mesoporous TiO2 photocatalyst for efficient degradation of organic dye via visible light photocatalysis.

A solvothermal method was used to synthesize the mesoporous TiO2, (1-3w %) Cu-doped mesoporous TiO2 membrane with the help of a bioreactor. To understand the physicochemical composition of all synthesized nanomaterials, the structure, morphology and crystallinity of the materials were studied using X-ray diffractometer (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform-infrared (FTIR), Energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry (CV). Under artificial light source (500 W mercury bulb) irradiations, the nano catalysts' catalytic effectiveness was examined for the azo dyes, namely Congo red. Cu-doping causes a shift in the light absorption of mTiO2 from the ultraviolet to the visible region. The 3w% Cu-doped mTiO2 photocatalyst exhibits lower band gap energy (2.6eV) than TiO2 which is 3.2 eV to efficiently utilize solar energy. As a result, the light absorption was shifted towards the visible spectrum. The recommended mTiO2 and (1, 2, 3) w% Cu-doped mTiO2 photocatalysts were used to photodegrade Congo red and methylene blue. For the degradation of CR, the mTiO2 photocatalyst exhibited 61% and 3w% Cu-doped mTiO2 demonstrated 99% photocatalytic performance after 50 min. A variety of scavengers were also utilized to distinguish the active species by catching the radicals and holes created during the process of photocatalytic degradation. CV indicates the presence of Cu2+ and Cu1+ in Cu-doped mTiO2. Oxygen vacancies and the electronegative surface of Cu1+ seem to perform the photocatalytic reduction of CR.

Graphene loaded TiO2 submicron spheres scattering layer for efficient dye-sensitized solar cell.

Dye-Sensitized Solar Cells (DSSCs) have attracted great attention due to environmentally friendly low-cost processing, excellent working ability in diffuse light, and potential to meet the power demands of future buildings due the true class of building integrated photovoltaics (BIPV). Nevertheless, DSSCs have relatively low photoconversion efficiency (PCE) due to multiple issues. Several strategies have been employed to enhance its PCE. For instance, bi-layered structure of photoelectrode i.e., mesoporous TiO2 transparent layer with top scattering layer was introduced which scatter light inside on large angles improves the harvesting ability of photoelectrode thus enhanced PCE. However, scattering layer is composed of aggregated small particles which offer sluggish electron transport due to multiple grain boundaries, consequently, unwanted recombination reaction which leads to poor PCE. This issue has been addressed for transparent layer immensely but ignored for scattering layer. Mostly for scattering layer in previous studies novel structures have been proposed to enhance scattering properties and dye adsorption only. Therefore, in this study for the first time presenting dual functional graphene/TiO2 scattering layer in which solvent exfoliated graphene is incorporated in TiO2 submicron spheres which enhanced electron transport properties, while submicron spheres scatter light effectively. Scattering and electron transport characteristics of DSSCs are thoroughly investigated with the function of graphene loading. Electrochemical impedance spectroscopy (EIS) has revealed that diffusion coefficient length and coefficient and conductivity attained maximum value at 0.01 wt%. while other important parameters such as electron lifetime and electron density in conduction band have been improved till 0.020 wt% graphene loading. However, results indicated that with 0.01 w% graphene 33% higher PCE was achieved than without scattering layer and 13% higher than scattering layer without graphene. The depraving in PCE at >0.01 wt% graphene despite of excellent electron transport improvement is attributed to the loss of diffuse reflectance and higher optical absorption by graphene.

Hydrophobic ammonium based ionic liquids for efficient extraction of textile dyes from aqueous media: Extraction study and antibacterial evaluation.

Alizarin red S (ARS) extraction from aqueous medium was carried out using hydrophobic ionic liquids (ILs) containing trioctylammonium cation paired with 4-tert-butylbenzoate ([TOA][Butbenz] (IL1), 4-phenylbutanoate ([TOA][PheBut] (IL2), 3-4-dimethylbenzoate ([TOA][DMbenz] (IL3), naphthoate, ([TOA][Naph]) (IL4), salicylate ([TOA][Sali]) (IL5) and nonanedioate ([TOA]2[Nona]) (IL6). The findings demonstrated that all of the tested ILs were efficient for extracting ARS, however, [TOA]2[Nona] was more effective than others. For the extraction of ARS from the aqueous phase, the effects of various parameters including the initial pH of the dye solution, contact time, ILs to dye volume ratio (VIL:VW), dye concentration, temperature, and salt effect were investigated. The spontaneity of the liquid-liquid extraction of ARS from the aqueous phase to the IL phase was confirmed by thermodynamic parameters. More than 90% of the ARS was extracted from the aqueous phase to the IL phase throughout all experiments. Interaction of selected IL with dyes were confirmed using FTIR analysis. The standard bacterial strains of Escherichia coli (E. coli) ATCC BAA-2471 (gram negative) and Methicillin-resistant Staphylococcus (MRSA) ATCC 43300 (gram positive) were used for evaluating antibacterial activity. The lower dose (250 ppm), the ILs1, 2, 3, 4, 5, and 6 inhibited 0.40, 1.50, 6.50, 1.50, 2.50, and 0.50 mm growth of E. coli, and 4.0, 2.0, 16.50, 0.40, 5.0, and 3.50 mm growth of MRSA, respectively. The experimental findings confirmed that the present ILs can be utilized as an effective solvent for ARS and other dyes extraction from aqueous media.

Hydrothermally synthesized Ag-TiO2 nanofibers (NFs) for photocatalytic dye degradation and antibacterial activity.

This work successfully utilised eco-friendly green synthesis to produce Ag-TiO2 nanofibers (NFs). As pollution and energy limitations have become global issues, there is an ongoing need to develop more effective catalysts through straightforward and environmentally friendly methods. The Ag-TiO2 nanofibers (NFs) XRD pattern exhibits an anatase TiO2 and FCC crystal structure of Ag nanoparticles. The SEM investigation revealed a nanofiber-like surface morphology. The Ag-TiO2 nanofibers (NFs) exhibits an optical band gap energy is 2.5 eV. Methylene blue (MB), malachite green (MG), Congo red (CR), and crystal violet (CV) dye aqueous solutions were used to evaluate the photocatalytic performance of the synthesized Ag-modified TiO2 nanofibers (NFs) under direct sunlight irradiation. The effects of catalyst size on the efficient breakdown of MB dye were also investigated. The optimum catalyst concentration was found to be at 0.02 mg/mL. At 120 min of direct sunlight, the highest photosynthetic degradation efficiency (DE percentage) of 94% was achieved for MB dye. Ag-TiO2 nanofibers (NFs) have been demonstrated to have exceptional antibacterial activity against Gram-positive bacteria such as Staphylococcus aureus and Gram-negative bacteria E-Coli. Because of these great qualities, it seems likely that the Ag-TiO2 nanofibers (NFs) made could be a great photocatalyst for getting dye pollutants out of wastewater.

Energy, exergy, economic, environment, exergo-environment based assessment of amine-based hybrid solvents for natural gas sweetening.

Natural gas is the cleanest form of fossil fuel that needs to be purified from CO2 and H2S to diminish harmful emissions and provide feasible processing. The conventional chemical and physical solvents used for this purpose have many drawbacks, including corrosion, solvent loss, high energy requirement, and the formation of toxic compounds, which ultimately disrupt the process and affect the environment. Hybrid solvents have lately been researched to cater to these liabilities and enhance process economics. This study screened eight solvents based on CO2 selectivity viscosity, absorption enthalpy, corrosivity, working capacity, specific heat, and vapor pressure. From the screened solvents, ten cases of hybrid solvents are simulated and optimized on Aspen HYSYS®. Furthermore, 5Es (Energy, Exergy, Economic, Environmental, and Exergy-environmental) analyses were performed on optimized cases, and results were compared with the base case, MEA (30 wt%). The hybrid blend of Sulfolane and MDEA with weight percentages of 6% and 24%, respectively, showed the highest energy savings of 20% concerning the base case. In addition, it offered 93% savings in exergy destruction and 17.26% in the total operating cost of the process. It is also promising to the environment due to reduced entropy sent to the ecosystem and controlled CO2 emissions. Therefore, the blend of Sulfolane and MDEA is proposed to Supersede the conventional solvent MEA for the natural gas sweetening process.

Green Synthesis of Silver Nanoparticles Using Thespesia populnea Bark Extract for Efficient Removal of Methylene Blue (MB) Degradation via Photocatalysis with Antimicrobial Activity and for Anticancer Activity.

The green synthesis method was used to effectively fabricate Ag-NPs by using Thespesia populnea bark extract. The structural, morphological, elemental composition, and optical properties of as-synthesized Ag-NPs were characterized by powder X-ray diffraction (P-XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), and UV-Vis spectroscopy. Their photocatalytic efficiency as a photocatalyst was examined by degradation of methylene blue (MB) dye under direct sunlight irradiation. After 120 minutes of sunlight irradiation, Ag-NPs show photocatalytic degradation efficiency (DE percent) of 92%. The hydroxyl and superoxide radicals were found to be responsible for biodegradation. To the best of our acquaintance, this is the first research to use Ag-NPs as a photocatalyst for the efficient degradation of MB dye and its antimicrobial activity by using Thespesia populnea bark extract. The cytotoxic viability against SK-MEL cell line with a median inhibitory concentration (IC50) of 45 µL/mg proved its potent anticancer property. Based on the findings, the study revealed the significance of as-synthesized green Ag-NPs over other physically/chemically prepared Ag-NPs.