Materials Science for Energy Technologies最新文献

Energy storing devices plays a major role in the development of technology. We synthesized carbon-based nanocomposites through a physical method and CuCo₂O₄ nanocomposites through a sol–gel technique calcined at 600 °C. From X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of CuCo₂O₄ nanocomposites which also shows some impurity phase of CuO nanoparticle. The average crystalline size found to be 45 nm. According to optical absorption analysis, the particles show maximum absorption in 256 nm and 369 nm in the UV region, while copper cobaltite doped with activated carbon (AC) shows broad absorption compared with copper cobaltite alone. Morphology studies shows agglomerate image in AC composites and hexagonal structures was formed in CuCo₂O₄ nanoparticles with average particle size of 100 nm. Atomic and weight percentages were recorded using energy dispersive X-ray analysis (EDAX). A good specific capacitance can be found from CV analysis, using electrochemical impedance spectroscopy (EIS), nanoparticles are shown to have different interface properties at the surface of electrodes. Using CuCo₂O₄ and its composite as positive and negative electrodes in cyclic voltammetry (CV) studies shows excellent electrochemical properties. In addition, CuCo₂O₄ with activated carbon is promising as a low-cost and good supercapacitor material.

Using first-principles calculations, in this piece of work, authors have investigated the physical properties of Ra₂LaNbO₆ double perovskite by employing the linearized augmented plane wave (LAPW) method. Structural and electronic properties are determined by using LDA, GGA (WC and PBE), LDA + mBJ, and GGA + mBJ potentials. We have found that Ra₂LaNbO₆ is an indirect band gap (E_g = 2.4 eV) semiconductor. Its elastic and thermodynamic parameters demonstrate its stability. Its optical study indicates that this material opens the door to its applications in optical devices such as photodetectors, solar cells, superlenses, optical fibers, filters, electromagnetic shielding devices, photovoltaic devices, etc. This material is very good for its practical implementation in thermoelectric devices as both p- and n-type material and extends the interest of experimentalists for further investigations. Thus, Ra₂LaNbO₆ is found thermodynamically stable and identified as a potential candidate for photovoltaic and thermoelectric devices.

Modern engineering applications continually strive to develop greater performance mechanical components with good microstructural stability, improved mechanical properties, corrosion resistance and decreased cost of repairing and maintenance. This necessitates the broad use of advanced high performance materials like high entropy alloys (HEAs). These alloys are created by combining five or more alloying elements in equal or substantial amount. About 5 to 35 at. % of the alloying element is present in HEAs. It is characterized primarily by greater entropy, slow diffusion, severe lattice distortion, and cocktail effects. Due to its advanced microstructural stability throughout a larger temperature span and for longer length of time, it demonstrates improved mechanical characteristics at ambient temperature, cryogenic temperature, and elevated temperature. The diversity of elemental contents and significantly higher mixing entropy of HEAs make them mechanically superior to classic metals and alloys. It also shows better strength to weight ratio. Hence, it qualifies as a possible structural and functional material for aeroengine applications. In this work, the studies on the HEAs are briefly reviewed. A basic explanation of the four core effects of HEAs is given. Discussion is held on microstructure and mechanical properties of HEAs. The processing routes for manufacturing of HEAs (arc melting, bridgman solidification, mechanical alloying and vapour deposition) are presented briefly. The influence of heat treatment on mechanical behavior and microstructure of HEAs is presented. The simulation approach of CALPHAD modeling for designing of HEAs is discussed briefly. The future scope for research and development of HEAs in aeroengine applications is briefed.

Nano-silicon is synthesized by hydrothermal method from rice husk, which has the advantage of using low temperature in an autoclave at 180 °C. Reduction of silica using a mixture of silica gel extracted from rice husks with Mg powder. The silica gel and Mg powder reaction produces nano-silicon. XRD diffractogram, it can be seen that Si-0.5, Si-0.6, and Si-0.7 form hkl (1 1 1), (2 2 0), (3 1 1), (4 0 0), (3 3 1), and (4 2 2). Raman spectra show peaks at the Raman shift of 520 cm⁻¹, XPS spectrum high scan Si2p peaks at 99 eV, indicating silicon, and at 103 eV, the oxide layer on nano-silicon. The isotherm adsorption graph using the BET method type IV isotherm graphs with surface areas are 18.60 m²g⁻¹ until 20.39 m²g⁻¹. Pore size using the BJH method shows 1.69 nm until 8.30 nm. SEM and TEM nano-silicon morphology images, the shape of the nano-silicon is spherical. The nano-silicon formed produces high-performance anode lithium-ion batteries with a discharge capacity of 1757 mAh g⁻¹, above 1000 mAh g⁻¹ for approximately 200 cycles.

The experiment was carried out by growing BaTiO₃ (Undoped or Li-doped) on p-type Si_(1 0 0) substrates using the Chemical Solution Deposition (CSD) method and spin coating at a rotational speed of 3000 rpm for 60 s, followed by heating at 850 °C. The characterization results show that the bandgap energy value of the thin film due to lithium doping reduces the bandgap energy value. This is presumably because the donor atom added to a semiconductor causes the allowable energy level to be slightly below the conduction band. The presence of this new band causes the thin film bandgap energy to decrease with a five-valent tantalum dip. The morphological properties showed that the BaTiO₃/Si_(1 0 0) thin film particles in the deposited lithium had a fairly homogeneous grain. With the addition of lithium acetate as a binder into barium titanate, the grain size is getting smaller because it is suspected that the lithium-ion radius is smaller than the barium-ion radius. Measurement of I-V on the thin film shows that the output voltage value increases with more light intensity hitting the surface of the thin film. The greater the light intensity, the greater the energy of the photons, so the electrons are easier to jump. The three things above (both electrical and morphological properties) conclude that the thin films grown have the potential for photovoltaics.

Recent concerns regarding climate change and rising energy costs have dramatically increased interest in using alternative energies, especially biomass energy which is carbon neutral. Hemp is among the fastest-growing plants with unique fiber characteristics. The objective of this study was to investigate the physical and chemical properties of hemp stalks of seven different clones and to assess their feasibility as a sustainable bioenergy resource. Seven clones (KU03, KU18, KU27, KU45, KU49, RPF1, and RPF2) of four-month-old hemp (Cannabis sativa) were used in this work. Physical properties, volatile content, fixed carbon, ash content, calorific value, chemical composition, ash composition, and metal element of the samples were investigated. The results revealed that hemp stalk had desirable fuel characteristics with high volatile substance, high heating value, low ash content, very low nitrogen content, and non-detectable sulfur. Selecting well-adapted clones and appropriate technology which can convert the hemp stalks to suitable bioenergy forms are important aspects of bioresource management. Based on our findings, some selected hemp clone biomass possessed excellent characteristics and great potential to be used as raw material for bioenergy production.

Different polylactic acid (PLA) thin films containing clarithromycin and a number of metal oxide nanoparticles (magnesium, titanium, zinc, and nickel) dioxides were created. Low dosages of metal oxides (0.01% by weight) and clarithromycin (0.5% by weight) were used to make transparent films. The role of metal oxide nanoparticles and clarithromycin as UV blockers for PLA photodegradation was looked at. The durability of polymeric materials is improved more by clarithromycin in combination with metal oxides than by clarithromycin alone in PLA films. An analysis of the weight loss, surface morphology, and changes in infrared spectra of irradiated polymeric blends revealed that nickel oxide and clarithromycin together function as effective UV blockers and offer PLA a high degree of protection. Nickel oxide nanoparticles were the best addition for PLA stability. Highly alkaline metal oxides are present. Contrarily, the heteroatom and aromatic nature of clarithromycin enables it to absorb damaging radiation and function as an ultraviolet absorption. Thus, the adaptability of PLA to photodegradation was significantly improved by using a mixture of metal oxide nanoparticles and clarithromycin.

In this study, S and Bi Co-doped carbon quantum dots were synthesized and their application for Cd(II) removal was investigated. All the experiments were performed in batch mode and effect Bi/S ratio on pH was investigated. It was observed that 12 pH is most suitable for fast removal of Cd²⁺. The optimized Bi/S ratio was further investigated for effect of adsorbent dosage, initial concentration of Cd(II). Addition of four scavenger solvent namely formaldehyde, acetic acid, ethanediamine and methanol was investigated for enhancement in the photocatalytic activity. Maximum removal efficiency was observed with ethandiamine ∼94% at 300 ppm as compared to formaldehyde (∼90.3%), methanol (∼86.7%) and acetic acid(∼86.3%) indicating that amine group is more suitable as scavenger molecule. Adsorption isotherms of Cd(II) on Bi/S doped on CQD were fitted for different adsorption isotherm model namely Langmuir, Freundlich and Temkin isotherms. Both Lanmguir and Temkin isotherm were observed to fit well with R² value above 98% as compared to Freundlich with lower R² value (∼95.3%), indicating that a combination of chemisorption phenomenon as well as availability of energy of electron could be responsible for the Cd(II) removal. Thermodynamic parameters both enthalpy change and entropy change were estimated as −10.76 kJ/mol and −11.2 kJ/mol K. All three parameters were negative indicating that the process was spontaneous and exothermic.

The coating materials, thickness and number of layers directly influence the reflectance and absorptance properties of the thin films. However, while selecting the materials for single and coatings, the substrate’s refractive index; bond layer, functional layer and protective layer have to be carefully chosen to obtain the desired reflectance and absorptance values. Hence, modelling and simulating the thin film coatings is essential before conducting the experiments to get meaningful results. The simulation results of single coatings have been discussed. Generally, glass is one of the widely used substrate materials for solar reflectors, aluminum is the optimal functional material, with a reflection of 93 % of light. Nickel would be a preferable functional layer with a reflection of 64 % and absorptance of 36 %, Si₃N₄ being the acceptable bond layers and protective layers with a reflection of 68 % some solar thermal receiver tube applications however research effort is being made to find alternate lightweight materials for this application. Polycarbonate has been chosen as an alternate material for the substrate because it is light in weight with a reflection of 93 %, which is durable and not fragile.