Search Results (7)

All-solid-state batteries (ASSBs) based on sulphide electrolytes are promising next-generation energy storage systems because they are expected to have improved safety, increased volumetric energy density, and a wide operating temperature range. However, side reactions at the cathode/electrolyte interface deteriorate the electrochemical performance and limit the commercialization of ASSBs. Surface coating of the cathode is an efficient approach for overcoming this issue. In this study, new Li₃BO₃ (LBO)-Li₃PO₄ (LPO) composites were applied as coating materials for high-Ni cathodes (NCM). PO₄-based materials (such as LPO) have been used as coating layers because of their good chemical stability in sulphide electrolytes. However, the ionic conductivity of LPO is slightly insufficient compared to those of generally used ternary oxides. The addition of LBO could compensate for the low ionic conductivity of LPO and may provide better protection against sulphide electrolytes owing to the effect of LBO, which has been used as a good coating material. As expected, the LBO-LPO composites (LBPO) NCM exhibited superior discharge capacity, rate capability, and cyclic performance compared to the pristine and LPO-coated NCMs. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) analyses confirmed that the LBPO coating on the cathodes successfully suppressed the byproduct formation and an undesirable interfacial layer, which are attributed to interfacial side reactions. This result clearly shows the potential of the LBPO coating as an excellent buffer layer to stabilise the oxide cathode/sulphide electrolyte interface. Full article

By using the chemical bath deposition approach, binary bismuth sulphides (Bi₂S₃) and chromium-doped ternary bismuth sulphides (Bi_2−xCr_xS₃) thin films were effectively produced, and their potential for photovoltaic applications was examined. Structural elucidation revealed that Bi₂S₃ deposited by this simple and cost-effective method retained its orthorhombic crystal lattice by doping up to 3 at.%. The morphological analysis confirmed the crack-free deposition, hence making them suitable for solar cell applications. Optical analysis showed that deposited thin films have a bandgap in the range of 1.30 to 1.17 eV, values of refractive index (n) from 2.9 to 1.3, and an extinction coefficient (k) from 1.03 to 0.3. From the Hall measurements, it followed that the dominant carriers in all doped and undoped samples are electrons, and the carrier density in doped samples is almost two orders of magnitude larger than in Bi₂S₃. Hence, this suggests that doping is an effective tool to improve the optoelectronic behavior of Bi₂S₃ thin films by engineering the compositional, structural, and morphological properties. Full article

Natural gas (NG) requires treatment to eliminate sulphur compounds and acid gases, including carbon dioxide (CO₂) and hydrogen sulphide (H₂S), to ensure that it meets the sale and transportation specifications. Depending on the region the gas is obtained from, the concentrations of acid gases could reach up to 90%. Different technologies are available to capture CO₂ and H₂S from NG and absorb them with chemical or physical solvents; occasionally, a mixture of physical and chemical solvents is employed to achieve the desired results. Nonetheless, chemical absorption is the most reliable and utilised technology worldwide. Unfortunately, the high energy demand for solvent regeneration in stripping columns presents an obstacle. Consequently, the present study proposes a novel, ternary-hybrid mixture of N-methyl diethanolamine (MDEA), amino ethyl ethanol amine (AEEA), and N-methyl 2-pyrrolidone (NMP) to overcome the issue and reduce the reboiler duty. The study employed high levels of CO₂ (45%) and H₂S (1%) as the base case, while the simulation was performed with the Aspen HYSYS^® V12.1 software to evaluate different parameters that affect the reboiler duty in the acid gas removal unit (AGRU). The simulation was first validated, and the parameters recorded errors below 5%. As the temperature increased from 35 °C to 70 °C, the molar flow of the CO₂ and H₂S in sweet gas also rose. Nevertheless, the pressure demonstrated an opposite trend, where elevating the pressure from 1000 kPa to 8000 kPa diminished the molar flow of acid gases in the sweet gas. Furthermore, a lower flow rate was required to achieve the desired specification of sweet gas using a ternary-hybrid blend, due to the presence of a higher physical solvent concentration in the hybrid solvent, thus necessitating 64.2% and 76.8%, respectively, less reboiler energy than the MDEA and MDEA + AEEA. Full article

In this paper, the electrochemical behavior of cysteine is described, using carbon paste electrodes (CPEs) modified with ternary silver-copper sulfide containing intrinsic silver at two pH values (pH 3 and 5). Experiments have revealed that presence of cysteine has a large impact on the electrochemical behavior of modified CPEs. Observed phenomena take place in solution, as well as at the surface of the modified CPEs, and can be applied for electroanalytical purposes. Based on the electrochemical behavior observed in the examined system, differential pulse voltammetry (DPV) was selected as an electroanalytical method for determination of cysteine. The effects of the various parameters on the electroanalytical signal, such as the amount of electroactive material, electroanalytical parameters, pH etc., were investigated using differential pulse voltammograms. The results indicated that electrochemical signal characterized with well-defined cathodic peak at 0.055 V vs. Ag/AgCl (3 M) in acetic buffer solution at pH 5 can be used for indirect electrochemical determination of cysteine. The optimization procedure revealed that the most sensitive and stabile electrode was that containing 5% modifier. The DPV response of the electrode, in the presence of cysteine, showed two different linear concentration ranges of 0.1 to 2.5 μM, and 5.6 to 28 μM. The explanation of the origin of two linear ranges is proposed. The lower concentration range was characterized by remarkable sensitivity of the 11.78 μA μM⁻¹, owing to the chosen indirect method of determination. The calculated limit of detection (LOD), as well as limit of quantification (LOQ) were 0.032 and 0.081 μM, respectively. The influence of interfering agents on the electroanalytical response was examined, and low or no interference on the DPVs was observed. The proposed method was validated and applied for the determination of cysteine in pharmaceutical preparations with satisfactory recoveries in the range of 97 to 101.7%. Full article

For photovoltaic applications, undoped and Ni²⁺ doped Bi₂S₃ thin films were chemically deposited onto glass substrates at room temperature. Elemental diffraction analysis confirmed the successful Ni²⁺ incorporation in the range of 1.0 to 2.0 at. %, while X-ray Diffraction analysis revealed that orthorhombic crystal lattice of Bi₂S₃ was conserved while transferring from binary to ternary phase. Scanning electron microscopy images reported homogeneous and crack-free morphology of the obtained films. Optoelectronic analysis revealed that the bandgap value was shifted from 1.7 to 1.1 eV. Ni²⁺ incorporation also improved the carrier concentration, leading to higher electrical conductivity. Resultant optoelectronic behavior of ternary Bi_2−x Ni_xS₃ thin films suggests that doping is proved to be an effectual tool to optimize the photovoltaic response of Bi₂S₃ for solar cell applications. Full article

Energy sufficiency is a critical requirement for the economic prosperity of modern countries. Efficient harnessing of solar energy using technologies such as the dye-sensitized solar cell could solve the energy problem which persistently plagues developing countries. Despite having a simple operational procedure and modest power conversion efficiency of 13.8%, the dye-sensitized solar cell consists of an expensive platinum counter electrode which makes commercial success futile. Thus, this review intends to establish the progress researchers have attained in the development of sulphide based counter electrodes as alternatives to platinum, thereby lowering cost of production. Metallic sulphides are good electrocatalysts and cheap, hence, they possess the necessary requirements for effective functional counter electrodes. Furthermore, ternary metallic sulphides are known to exhibit higher efficiencies stemming from the synergistic effect produced by the co-existence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability. Incorporation of metallic sulphides with carbon materials, which are exceptional electrical conductors, could potentially produce more efficient counter electrodes. In that regard, this review seeks to establish the effect recently developed composite counter electrodes comprising metallic sulphides and carbon-based materials have induced on the functionality of the counter electrode (CE). Full article

A dye-sensitised solar cell (DSSC) counter electrode (CE) plays a vital role in catalysing the conversion of triiodide ( ${\mathrm{I}}_3^{-}$ ) to iodide ions ( ${\mathrm{I}}^{-}$ ), thereby ensuring the completion of the repetitive cycle of electricity generation. The platinum CE, despite being the standard counter electrode in DSSCs, has drawbacks of platinum’s rarity and high cost. Platinum is an excellent redox catalyst, and consequently, it is the most sought-after metal for catalytic conversions. The huge demand for platinum in the automotive industry for vehicular catalytic converters, the pharmaceutical industry, and in oil refining, as well as other industries, has driven its price to unprecedented levels. The prohibitive price of platinum has caused newer thin film technologies, such as the DSSC which depends on the platinum CE, to be cost-ineffective, thus meaning they cannot compete with the better-established silicon-based solar cells. These problems have stagnated the development of the DSSC, which in turn has dampened larger commercialisation prospects for this thin film technology. With this in mind, this review paper focuses on recent progress in the research and development of alternative cost-effective materials to replace Pt-based CEs. Ternary alloys are amongst the possible alternatives that have been explored, yielding varied results. Alloys, especially ternary sulphides, selenides, and oxides, are attractive as alternatives as they are cheap and are easily fabricated. Ternary alloys also have a synergistic effect produced by the coexistence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability, thus making them ideal cost-effective materials to replace the Pt CE in DSSCs. This review intends to highlight the performance of ternary alloy counter electrodes through the analysis of charge transfer resistance and power conversion efficiencies. Focus is also given to the restrictions and impediments to the attainment of higher power conversion efficiency in alternative CEs. The advances in fabrication of simple ternary alloys, as well as more advanced hierarchical nanostructured counter electrodes, are discussed here in detail. Results obtained to date indicate that the efficiencies of ternary alloy counter electrodes are still below that of the platinum counter electrode, and hence more research is required to enhance their efficiencies. Full article