Tailoring confined CdS quantum dots in polysulfone membrane for efficiently durable performance in solar-driven wastewater remediating systems.

In this work, CdS quantum dots (QDs) were successfully confined in polysulfone membrane (PSM) to develop a photoactive membrane under solar illumination that was suited in wastewater remediating system. The CdS@PSM membranes were prepared using the nonsolvent induced phase separation (NIPS) approach. Optical measurements show the confinement of CdS quantum dots (QDs) in the PS matrix within the narrowest band gap (2.41 eV) at 5 wt% loading. PS has two strong emission peaks at 411 and 432 nm due to photoelectron-hole recombination on pure PSM's surface. Adding 1 wt% CdS QDs to PSM reduced the earlier peak and blue-shifted the latter, within the appearance of three emission peaks attributed to the near band-edge emission of confined CdS QDs. Overloading CdS reduced all emission peaks. Moreover, fluorimetric monitoring of •OH radicals indicates that PSM produces the least amount of photogenerated •OH radicals while CdS@PSM(5 wt%) achieved the highest productivity. Examining the developed membranes in detoxifying methylene blue (MB) from aqueous solution of natural pH 8.1 showed weak adsorption in dark over 90 min of contact while switching to solar illumination significantly photodegrade MB where the degradation efficiency starts from 49% for pure PSM to 79% for CdS@PSM(5 wt%). Influence of pH was found crucial on photodegradation efficacy. Acidic pH 3 showed the weakest photodegradation efficacy, while the alkaline pH 12 was 18.88 times more effective. The used CdS@PSM (5 wt%) was successfully photo-renovated by soaking in 10 mL of NaOH solution under Solar illumination for 15 min to be used in 4 consecutive photodegradation cycles with insignificant decrease in efficacy. These findings are promising and could lead to a high-efficiency, sustainable photocatalytic suite.

Macroscopic Freestanding Nanosheets with Exceptionally High Modulus.

Macroscopic single-wall carbon nanotube (SWCNT) films of nanoscale thickness have significant potential for an array of applications that demand thin, transparent, conductive coatings. Using macroscopic micrometer thick polystyrene sheets as a reference, we characterize the elastic response of freestanding multifunctional SWCNT nanosheets possessing both exceptionally high Young's modulus and good durability. Thin SWCNT films (20-200 nm thick) asymmetrically "doped" with dilute concentrations of superparamagnetic colloids were suspended in ethanol as freestanding nanosheets. Through repeated and controlled deformation in an external magnetic field, we measure the temporal relaxation of nanosheet curvature back to equilibrium. From the relaxation time and its dependence on nanosheet thickness and length, we extract the SWCNT nanosheet modulus through a simple viscoelastic model. Our results are consistent with nearly ideal SWCNT rigidity percolation with moduli approaching 200 GPa and limited plasticity for sufficiently thick sheets, which we attribute to the screening of van der Waals interactions by the surrounding solvent and the macroscopic nature of the deformation.

Enhancing the Elasticity of Ultrathin Single-Wall Carbon Nanotube Films with Colloidal Nanocrystals.

Thin bilayers of contrasting nanomaterials are ubiquitous in solution-processed electronic devices and have potential relevance to a number of applications in flexible electronics. Motivated by recent mesoscopic simulations demonstrating synergistic mechanical interactions between thin films of single-wall carbon nanotubes (SWCNTs) and spherical nanocrystal (NC) inclusions, we use a thin-film wrinkling approach to query the compressive mechanics of hybrid nanotube/nanocrystal coatings adhered to soft polymer substrates. Our results show an almost 2-fold enhancement in the Young modulus of a sufficiently thin SWCNT film associated with the presence of a thin interpenetrating overlayer of semiconductor NCs. Mesoscopic distinct-element method simulations further support the experimental findings by showing that the additional noncovalent interfaces introduced by nanocrystals enhance the modulus of the SWCNT network and hinder network wrinkling.

Rigidity of lamellar nanosheets.

Lamellar nanosheets of contrasting materials are ubiquitous in functional coatings and electronic devices. They also represent a unique paradigm for polymer nanocomposites. Here, we use fluid-assembled lamellar nanosheets - alternating layers of polymer and single-wall carbon nanotubes (SWCNTs) - to gain insight into the flexural mechanics of such hybrid films. Specifically, we measure the modulus and yield strain as a function of both layer thickness and the total number of layers. Overall, we find that the multi-layered films exhibit the greatest synergistic effects near a layer thickness of 20 nm or less, which we relate to the characteristic width of the SWCNT-polymer interface. For all layer thicknesses, we find that the nanosheets have realized the bulk limit by six layers. Our results have potentially profound implications for controlling the rigidity and durability of polymer nanocomposites, thin hybrid films and flexible heterojunctions.

Effect of Asymmetric Fins on Thermal Performance of Phase Change Material-Based Thermal Energy Storage Unit.

Phase change material (PCM)-based thermal energy storage units (TESU) have very low thermal conductivity that compromise their charging and discharging rate. The present study focuses on an enhancement in charging rate as well as an increase in the uniformity of the melting rate. A rectangular cavity consisting of two horizontal partial fins is studied. The horizontal partial fins are placed symmetrically in a PCM-based TESU. In the current work, the melting rate of PCM was enhanced using asymmetric arrangement while keeping all other parameters the same, thus showing the positive effect of asymmetric configuration in such storage systems. The position and the pitch of each fin is optimized to improve heat transfer characteristics of the TESU. The numerical investigation of the problem is performed. TESU with asymmetrically placed fins show better performance in terms of higher charging rate as well as uniformity of the charging rate. The asymmetric placement of the fins suggested by present study increased the charging rate by 74.3% on average as compared to the symmetrically placed fins in the storage system. The charging rate uniformity is improved by 43.7%. The asymmetric fin's placement conserved the convection strength for a longer melting duration and so increased the Nusselt number by 80.2% as compared to the symmetrically placed fins. Thus, it can be concluded that the performance of asymmetric fins is better in the charging of PCMs than the symmetrically placed fins in a PCM-based TESU.

Tailoring the interfacial surfaces of tungsten and molybdenum tungsten disulfide electrodes for hybrid supercapacitors.

The layered structures of tungsten disulfide (WS2) and molybdenum tungsten disulfide (MoWS2) are considered as the most promising electrode materials for energy storage devices. Herein, MS (magnetron sputtering) is required for the deposition of WS2 and MoWS2 on the surface of the current collector to attain an optimized layer thickness. The structural morphology and topological behavior of the sputtered material were examined via X-ray diffraction and atomic force microscopy. Three-electrode assembly was used to start the electrochemical investigations to identify the most optimal and effective sample among WS2 and MoWS2. CV (cyclic voltammetry), GCD (galvanostatic charging discharging), and EIS (electro-impedance spectroscopy) techniques were employed to analyze the samples. After preparing WS2 with optimized thickness as the superior performing sample, a hybrid device was designed as WS2//AC (activated carbon). With a remarkable cyclic stability of 97% after 3000 continuous cycles, the hybrid supercapacitor generated a maximum energy density (Es) value of 42.5 W h kg-1 and 4250 W kg-1 of power density (Ps). Besides, the capacitive and diffusive contribution during the charge-discharge process and b-values were calculated by Dunn's model, which lay in the 0.5-1.0 range and the fabricated WS2 hybrid device was found to have a hybrid nature. The outstanding outcomes of WS2//AC make it suitable for future energy storage applications.

Effect of Rice Husk and Wood Flour on the Structural, Mechanical, and Fire-Retardant Characteristics of Recycled High-Density Polyethylene.

Given the rising consumption of plastic products, it is becoming imperative to prioritize the recycling of plastic items as a solution to reducing plastic waste and environmental pollution. In this context, this research focuses on assessing the impact of incorporating rice husk and wood flour into recycled high-density polyethylene (rec-HDPE) to analyze its mechanical properties, flammability, and thermal stability. The combined rec-HDPE content of wood flour and rice husk varied between 0% and 20%. The rec-HDPE content of maleic anhydride grafted polyethylene (MAPE) was fixed at 3%. Mechanical characteristics such as flexural, tensile, and impact strengths were assessed. Cone calorimetry (CC) tests, limited oxygen index (LOI) tests, and horizontal and vertical burning tests were performed to determine the flammability or fire retardancy of these composites. On the other hand, to characterize the thermal characteristics of these composites, thermogravimetric analysis (TGA) was used. To further characterize the fluctuation in these characteristics, scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) studies were carried out. The mechanical characteristics were found to be increased in response to adding rice husk or wood flour. An 8% increase in tensile strength and a 20% increase in elastic modulus enhancement were recorded for a 20% rice husk-added composite. SEM revealed the reason for the variation in tensile properties, based on the extent of agglomeration and the extent of uniform distribution of fillers in rec-HDPE. Following these lines, the 20% rice husk-added composite also showed a maximum increase of around 6% in its flexural strength and a maximum increase of 50% in its flexural modulus. A decrease in impact strength was recorded for rice husk and wood flour-reinforced composites, compared with unreinforced rec-HDPE. Hybrid composites displayed a lack of mechanical strength due to changes in their nature. FTIR tests were performed for a much more elaborate analysis to confirm these results. Twenty percent of rice husk-added rec-HDPE displayed the best thermal properties that were tested, based on TGA and derivative thermogravimetric (DTG) analysis. This 20% composite also displayed the best fire-retardancy characteristics according to UL 94 tests, cone calorimetry tests, and limited oxygen index tests, due to the barrier created by the silica protective layer. These tests demonstrated that the incorporation of both fillers-rice husk and wood flour-effectively enhanced the thermal, mechanical, and fire-retardant attributes of recycled HDPE.

Interaction of a Phospholipid and a Coagulating Protein: Potential Candidate for Bioelectronic Applications.

In the present communication, we have investigated the interaction between a biomembrane component 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and a coagulating protein protamine sulfate (PS) using the Langmuir-Blodgett (LB) technique. The π-A isotherm, π-t characteristics, and analysis of isotherm curves suggested that PS strongly interacted with DOPC, affecting the fluidity of the DOPC layer. Electrical characterization indicates that PS as well as the PS-DOPC film showed resistive switching behavior suitable for Write Once Read Many (WORM) memory application. Trap-controlled space charge-limited conduction (SCLC) was the key mechanism behind such observed switching. The presence of DOPC affected the SCLC process, leading to lowering of threshold voltage (V Th), which is advantageous in terms of lower power consumption.

Characterization and Modeling Quality Analysis of Edible Oils Using Electrochemical Impedance Spectroscopy.

The dielectric characteristics of six culinary oils were measured over the frequency range of 0.01 Hz-100 kHz. The results showed that the dielectric constants of oils had the same frequency relationship (i.e., they decreased with increasing frequency). The dielectric constants at lower frequencies for olive oil A, olive oil B, sesame oil, Nigella sativa, sunflower oil, and corn oil are approximately 2.75, 2.5, 2.0, 1.75, 1.5, and 0.9. An FT-IR analysis showed that the spectral differences were very small, because most vegetable oils contain the same type of fatty acids. The model built using COMSOL Multiphysics for the potential and electric field distributions for different oils and used to calculate the dielectric constant was simulated under various conditions in the AC/DC module. The model results were compared with the experimental results, which showed satisfactory convergence between them. The experimental and model results obtained in this study could be useful for evaluating the edible oil quality.

Converting Sewage Water into H2 Fuel Gas Using Cu/CuO Nanoporous Photocatalytic Electrodes.

This work reports on H2 fuel generation from sewage water using Cu/CuO nanoporous (NP) electrodes. This is a novel concept for converting contaminated water into H2 fuel. The preparation of Cu/CuO NP was achieved using a simple thermal combustion process of Cu metallic foil at 550 °C for 1 h. The Cu/CuO surface consists of island-like structures, with an inter-distance of 100 nm. Each island has a highly porous surface with a pore diameter of about 250 nm. X-ray diffraction (XRD) confirmed the formation of monoclinic Cu/CuO NP material with a crystallite size of 89 nm. The prepared Cu/CuO photoelectrode was applied for H2 generation from sewage water achieving an incident to photon conversion efficiency (IPCE) of 14.6%. Further, the effects of light intensity and wavelength on the photoelectrode performance were assessed. The current density (Jph) value increased from 2.17 to 4.7 mA·cm-2 upon raising the light power density from 50 to 100 mW·cm-2. Moreover, the enthalpy (ΔH*) and entropy (ΔS*) values of Cu/CuO electrode were determined as 9.519 KJ mol-1 and 180.4 JK-1·mol-1, respectively. The results obtained in the present study are very promising for solving the problem of energy in far regions by converting sewage water to H2 fuel.

Effect of Au Plasmonic Material on Poly M-Toluidine for Photoelectrochemical Hydrogen Generation from Sewage Water.

This study provides H2 gas as a renewable energy source from sewage water splitting reaction using a PMT/Au photocathode. So, this study has a dual benefit for hydrogen generation; at the same time, it removes the contaminations of sewage water. The preparation of the PMT is carried out through the polymerization process from an acid medium. Then, the Au sputter was carried out using the sputter device under different times (1 and 2 min) for PMT/Au-1 min and PMT/Au-2min, respectively. The complete analyses confirm the chemical structure, such as XRD, FTIR, HNMR, SEM, and Vis-UV optical analyses. The prepared electrode PMT/Au is used for the hydrogen generation reaction using Na2S2O3 or sewage water as an electrolyte. The PMT crystalline size is 15 nm. The incident photon to current efficiency (IPCE) efficiency increases from 2.3 to 3.6% (at 390 nm), and the number of H2 moles increases from 8.4 to 33.1 mmol h-1 cm-2 for using Na2S2O3 and sewage water as electrolyte, respectively. Moreover, all the thermodynamic parameters, such as activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*), were calculated; additionally, a simple mechanism is mentioned for the water-splitting reaction.

Influence of VO2 based structures and smart coatings on weather resistance for boosting the thermochromic properties of smart window applications.

Vanadium dioxide (VO2)-based energy-saving smart films or coatings aroused great interest in scientific research and industry due to the reversible crystalline structural transition of VO2 from the monoclinic to tetragonal phase around room temperature, which can induce significant changes in transmittance and reflectance in the infrared (IR) range. However, there are still some obstacles for commercial application of VO2-based films or coatings in our daily life, such as the high phase transition temperature (68 °C), low luminous transmittance, solar modulation ability, and poor environmental stability. Particularly, due to its active nature chemically, VO2 is prone to gradual oxidation, causing deterioration of optical properties during very long life span of windows. In this review, the recent progress in enhancing the thermochromic properties of VO2-hybrid materials especially based on environmental stability has been summarized for the first time in terms of structural modifications such as core-shell structures for nanoparticles and nanorods and thin-films with single layer, layer-by-layer, and sandwich-like structures due to their excellent results for improving environmental stability. Moreover, future development trends have also been presented to promote the goal of commercial production of VO2 smart coatings.

Exploring the electrochemical performance of copper-doped cobalt-manganese phosphates for potential supercapattery applications.

The significant electrochemical performance in terms of both specific energy and power delivered via hybrid energy storage devices (supercapattery) has raised their versatile worth but electrodes with flashing electrochemical conduct are still craved for better performance. In this work, binary and ternary metal phosphates based on copper, cobalt, and manganese were synthesized by a sonochemical method. Then, the compositions of copper and cobalt were optimized in ternary metal phosphates. The structural studies and morphological aspects of synthesized materials were scrutinized by X-ray diffraction and scanning electron microscopy. Furthermore, the electrochemical characterizations were performed in three- and two-cell configurations. The sample with equal compositions of copper and cobalt (50/50) demonstrates the highest specific capacity of 340 C g-1 at a current density of 0.5 A g-1 among all. This optimized composition was utilized as a positive electrode material in a supercapattery device that reveals a high specific capacity of 247 C g-1. The real device exhibits an excellent energy density of 55 W h kg-1 while delivering a power density of 800 W kg-1. Furthermore, the device was able to provide an outstanding specific power of 6400 W kg-1 while still exhibiting a specific energy of 19 W h kg-1. The stability potential of the device was tested for 2500 continuous charge and discharge cycles at 8 A g-1. Excellent capacitive retention of 90% was obtained, which expresses outstanding cyclic stability of the real device. A theoretical study was performed to investigate the capacitance and diffusion-controlled contribution in the device performance using Dunn's model. The maximum diffusion-controlled contribution of 85% was found at 3 mV s-1 scan rate. The study demonstrates the utilization of ternary metal phosphates as self-supported electrode materials for potential energy storage applications.

Electronic and optical properties of bulk and surface of CsPbBr3 inorganic halide perovskite a first principles DFT 1/2 approach.

This work aims to test the effectiveness of newly developed DFT-1/2 functional in calculating the electronic and optical properties of inorganic lead halide perovskites CsPbBr3. Herein, from DFT-1/2 we have obtained the direct band gap of 2.36 eV and 3.82 eV for orthorhombic bulk and 001-surface, respectively. The calculated energy band gap is in qualitative agreement with the experimental findings. The bandgap of ultra-thin film of CsPbBr3 is found to be 3.82 eV, which is more than the expected range 1.23-3.10 eV. However, we have found that the bandgap can be reduced by increasing the surface thickness. Thus, the system under investigation looks promising for optoelectronic and photocatalysis applications, due to the bandgap matching and high optical absorption in UV-Vis (Ultra violet and visible spectrum) range of electro-magnetic(em) radiation.

Cobalt-manganese-zinc ternary phosphate for high performance supercapattery devices.

State of the art supercapatteries have received considerable attention for their significant electrochemical performance; however, electrode materials with enhanced charge storage capabilities are desired. Here, we report the synthesis of mixed metal phosphate nanomaterials with different concentrations via a sonochemical approach. Initially, binary metal phosphates based on zinc, cobalt, and manganese were synthesized. Then, the composition of zinc and cobalt was optimized in ternary metal phosphates. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques were utilized to examine the surface morphology, elemental analysis and crystal structure of as-synthesized nanomaterials. The electrochemical characterizations were performed in a three cell configuration. Zn0.50Co00.50Mn(PO4)2 delivers the optimum performance with a specific capacity of 1022.52 C g-1 (specific capacitance of 1704.21 F g-1) at 1.2 A g-1. This optimized material was further engaged in an asymmetric device (supercapattery) as a positive electrode material to explore the real device performance. The supercapattery device was found to have an impressive specific energy of 45.45 W h kg-1 at 0.5 A g-1 and provide a remarkable specific power of 4250 W kg-1 at 5 A g-1 current density. The device exhibits excellent capacity preservation of 93% examined after 1500 charge discharge cycles. In addition, to scrutinize the supercapattery performance in terms of capacitive and diffusion controlled processes, a simulation approach was adopted. The real device comprises a capacitive contribution of 8.42% at 3 mV s-1 and 66.56% at 100 mV s-1. This novel progress in ternary metal phosphates results in a fine electrode material for high performance supercapattery applications.

Impact of Co2+ Substitution on Microstructure and Magnetic Properties of CoxZn1-xFe2O4 Nanoparticles.

In the present work, we synthesized CoxZn1-xFe2O4 spinel ferrite nanoparticles (x= 0, 0.1, 0.2, 0.3 and 0.4) via the precipitation and hydrothermal-joint method. Structural parameters were cross-verified using X-ray powder diffraction (XRPD) and electron microscopy-based techniques. The magnetic parameters were determined by means of vibrating sample magnetometry. The as-synthesized CoxZn1-xFe2O4 nanoparticles exhibit high phase purity with a single-phase cubic spinel-type structure of Zn-ferrite. The microstructural parameters of the samples were estimated by XRD line profile analysis using the Williamson-Hall approach. The calculated grain sizes from XRPD analysis for the synthesized samples ranged from 8.3 to 11.4 nm. The electron microscopy analysis revealed that the constituents of all powder samples are spherical nanoparticles with proportions highly dependent on the Co doping ratio. The CoxZn1-xFe2O4 spinel ferrite system exhibits paramagnetic, superparamagnetic and weak ferromagnetic behavior at room temperature depending on the Co2+ doping ratio, while ferromagnetic ordering with a clear hysteresis loop is observed at low temperatures (5K). We concluded that replacing Zn2+ ions with Co2+ ions changes both the structural and magnetic properties of ZnFe2O4 nanoparticles.