Materials Science for Energy Technologies最新文献

In this study, the influence of p-type doping with Na atoms on the optical bandgap and electrical conductivity of a series of bismuth ferrites (BiFeO₃) synthesized by a low-cost solid-state method was evaluated. To identify the properties that influenced the bandgap and electrical response of the samples, the phase of interest was identified and quantified by X-ray diffraction (XRD), the morphological characteristics were determined by scanning electron microscopy (SEM). Structural properties were elucidated by spectroscopic techniques and finally the optical response (indirect bandgap) was measured by ultraviolet–visible spectroscopy (UV–Vis) and electrical response (conductivity) by solid-state electrochemical impedance spectroscopy (SS-IES). The results of this work demonstrated that the optical and electrical response of the series of Na-doped BiFeO₃ samples is dependent on at least eight structural and morphological variables (sodium ratio, purity, unit cell volume, oxygen vacancy concentration, crystalline domain size, structural microdeformations, particle size and Warburg-type resistive phenomena). Among the most relevant results, the influence of purity, intrinsic and physical defects was identified, observing a decrease of the electrical resistance and energy gap with the presence of Na.

The solid-state zinc-ion battery (ZIB) is environmentally friendly, cost effective, and extremely safe, which are essential features for alternative sustainable energy storage systems. Herein, a polymer composite electrolyte (PCE) is successfully developed through a facile solution-casting approach from a thermo-responsive copolymer-based electrolyte and layered ternary carbide (Ti₃AlC₂). The thermo-responsive copolymer demonstrated synergistic mechanical properties through the addition of an appropriate plasticizer and a zinc salt. This combination suggests that the material possesses thermal self-protection capabilities due to its anti-Arrhenius ionic-conducting behavior. However, parasitic reactions and dendrite formation hindered the achievement of its full potential. The incorporation of Ti₃AlC₂ or MAX phase can mitigate the above obstacles, enhancing electrochemical performance with excellent flexibility and maintainable self-extinguishing. The solid-state ZIB benefits from the well-designed PCE with the expanding layer interspacing, delivering a remarkably high capacity (336 mAh g⁻¹ at 0.1 A g⁻¹) and energy density of 242 Wh kg⁻¹. This is achieved due to the Ti₃AlC₂′s ability to immobilize or entrap triflate anions via electrostatic forces. Therefore, the designed PCE is a promising step toward the development of flexible solid electrolytes in ZIBs.

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.

Nanoindentation technique is generally used for measuring thinfilm mechanical properties such as hardness, modulus and stiffness. Nanoindentation of ceramic thinfilms of SiO_2, Si₃N₄ and Al₂O₃ was deposited by radio-frequency (RF) magnetron sputtering on the stainless steel (SS304) substrates using a nanoindenter. Under varied sputtering conditions, the “as-deposited” film was amorphous. The as-deposited thin film had a thickness of 200 nm. The amorphous film was loaded/unloaded only once while operating in load control mode. Hardness and Young's modulus, two mechanical properties of the ceramic thinfilms, were also measured. When SiO₂, Si₃N₄, and Al₂O₃ thinfilms are deposited onto stainless steel substrates using an RF magnetron sputtering, the roughness of the ceramic thinfilms is in the range of 8 to 12 nm. The nanoindentation results were compared, the hardness of the coatings is in the range of 6 to 9 GPa, and these ceramic coatings can be used as an adhesive layer for multilayer thin film coating.

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.

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.

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.

The semiconductor oxide material titanium dioxide (TiO₂) has a number of strategic uses, such as an antimicrobial, self-cleaning, photocatalyst, and dye-sensitized solar cell (DSSC). Despite the fact that his substance is naturally obtained from the ilmenite (FeTiO₃) mineral, there have been few investigations in this field. This work produced heterogenous TiO₂ nanocrystals from ilmenite extraction, which were then subjected to post-hydrothermal treatment at a range of temperatures of 80, 100, 120, and 150 °C. In the present study, it was examined how temperature change affected the optical characteristics, crystal structure, and prospective integration of TiO₂ nanocrystals into DSSC. The obtained TiO₂ nanocrystals were identified as anatase phase by the X-ray diffraction analysis. As a result of raising the post-hydrothermal temperature from 80 to 150 °C, the crystallite size of heterogenous TiO₂ nanocrystals was successfully enhanced from 58.09 to 72.48 nm. The band gap energy (E_g) may be lowered from 2.81 to 2.65 eV by increasing the size of the crystallites. The greatest open circuit voltage (V_oc) measured by the voltage test findings was 16.80 mV. According to the study's findings, heterogenous TiO₂ nanocrystals synthesized from the ilmenite mineral might be used in dye-sensitized solar cell applications.

Currently the world is facing significant challenges of meeting the rising demands of production of green energy. Clean energy technology development has received a lot of attention because of increasing energy shortages and aggravating environmental degradation. It is critical to address these challenges by developing materials that facilitate carbon-free technologies. MXenes, an emerging member of the 2D nanomaterials family, has distinctive features in terms of clean energy production and storage. This review analyzes various MXenes synthesis methods based on several key factors. The review focuses on MXenes' applications in energy storage devices, particularly in rechargeable batteries and supercapacitors. MXenes exhibit exceptional electrochemical performance due to their high specific surface area, excellent electrical conductivity, and unique interlayer spacing, enabling efficient charge storage and fast ion diffusion. We discuss their implementation as electrode materials in lithium-ion batteries, sodium-ion batteries, lithium-sulphur batteries, metal air batteries and supercapacitors. Moreover, the review examines the applications of MXenes in hydrogen (H₂) production technologies. MXenes have shown tremendous potential as photo/electrocatalysts for water splitting, a key process in renewable hydrogen production. Their unique surface chemistry and tunable electronic properties enable efficient hydrogen evolution reaction (HER) activity. We discuss the recent advancements in developing MXene-based photo/electrocatalysts with their exceptional catalytic performance and durability. Furthermore, we highlight the challenges and prospects associated with MXenes' applications in energy storage and H₂ production. Strategies for improving the stability, scalability, and overall performance of MXenes are discussed. This review not only provides a comprehensive analysis of the recent research efforts but also serves as a guide for future research directions in utilizing MXenes to address the global energy and sustainability challenges.

This research describes the synthesis of the ferroelectric perovskite Na_0.02Bi_0.98FeO_3-δ using a low-cost solid-state method starting from a bismuth ferrite BiFeO₃ structure in order to obtain a material with improved properties for photovoltaic applications. The synthesized materials were characterized by X-ray Diffraction (XRD) technique to determine the effective synthesis conditions for six undoped BiFeO₃ samples obtained at different calcination temperatures and quantified by Rietveld® refinement of diffraction patterns, finding homogeneous phase formation at 810 °C under laboratory conditions. The effective synthesis temperature allowed obtaining a stable perovskite-type material, doped with Na⁺ and its structural characterization by XRD showed a structural modification in the unit cell with respect to BiFeO₃ due to the incorporation of sodium cation. The binding energies determined by X-ray photoelectron spectroscopy (XPS) confirmed the formation of the main crystalline phase and the insertion of Na⁺ cations inside perovskite structure. The morphological characterization by scanning electron microscopy (SEM) of the synthesized material showed the formation of two stable morphologies: Bi₂Fe₄O₉ and Na_0.02Bi_0.98FeO_3-δ as the predominant phase. The optical characterization by Raman spectroscopy allowed identifying variations in the vibration modes of the perovskite doped with respect to undoped bismuth ferrite. The variation of the optical bandgap was determined using the Tauc’s equation and the electrical characterization by solid state electrochemical impedance spectroscopy (SS-EIS) demonstrated an increase in electrical conductivity, at room temperature, by the Na⁺ doped perovskite, proving an optimal behavior for its potential uses as a semiconductor. The results indicate that the current methodology is promising for the low-cost production of Na_0.02Bi_0.98FeO_3-δ type perovskites for photovoltaic applications.