RESUMO
In this study, BaZr0.87Y0.1M0.03O3-δ perovskite electrolytes with sintering aids (M = Mn, Co, and Fe) were synthesized by a sustainable approach using spinach powder as a chelating agent and then compared with chemically synthesized BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes for intermediate temperature SOFCs. This is the first example of such a sustainable synthesis of perovskite materials with sintering aids. Structural analysis revealed the presence of a cubic perovskite structure in BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) samples synthesized by both green and conventional chemical methods. No significant secondary phases were observed in the samples synthesized by a sustainable approach. The observed phenomena of plane shift were because of the disparities between ionic radii of the dopants, impurities, and host materials. The surface morphology analysis revealed a denser microstructure for the electrolytes synthesized via green routes due to metallic impurities in the organic chelating agent. The absence of significant impurities was also observed by compositional analysis, while functional groups were identified through Fourier-transform infrared spectroscopy. Conductivity measurements showed that BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes synthesized by oxalic acid have higher conductivities compared to BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes synthesized by the green approach. The button cells employing BaZr0.87Y0.1Co0.03O3-δ electrolytes synthesized by the chemical and green routes achieved peak power densities 344 and 271 mW·cm-2 respectively, suggesting that the novel green route can be applied to synthesize SOFC perovskite materials with minimal environmental impact and without significantly compromising cell performance.
RESUMO
In this study, the laser-induced kohl plasma is produced in the vicinity of the transverse magnetic field (B) of 0.8 T. A Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) pulse laser (λ = 1064 nm, E = 100 mJ, τl = 8 ns) is focused to produce the kohl plasma with and without a B, and the plasma emissions are recorded using a laser-induced breakdown spectroscopy (LIBS) spectrometer. The comparison of the emission spectra shows that most of the emission line intensities are reduced due to the field. However, except for a few lines which are enhanced up to three times. However, the plasma parameters such as electron temperature (Te), electron number density (Ne), and plasma frequency (Êp) have been increased. Furthermore, thermal beta (ßt) is also estimated analytically, and its value is smaller than one (ß < 1) for all samples, which confirmed the evidence of magnetic confinement effects. According to the analysis of the kohl emission spectrum, several elements were detected (Pb, Ca, Mg, Fe, Cr, and Zn), among which lead (Pb) and chromium (Cr) may cause chronic health effects like contact dermatitis and neurological diseases. A calibration-free LIBS (CF-LIBS) method is used for the quantitative elemental analysis of the detected elements, which yields Pb as 15-74% and Cr as 3%, which exceed the permissible limit for kohl.
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The massive use of non-renewable energy resources by humankind to fulfill their energy demands is causing severe environmental issues. Photocatalysis is considered one of the potential solutions for a clean and sustainable future because of its cleanliness, inexhaustibility, efficiency, and cost-effectiveness. Significant efforts have been made to design highly proficient photocatalyst materials for various applications such as water pollutant degradation, water splitting, CO2 reduction, and nitrogen fixation. Perovskite photocatalyst materials are gained special attention due to their exceptional properties because of their flexibility in chemical composition, structure, bandgap, oxidation states, and valence states. The current review is focused on perovskite materials and their applications in photocatalysis. Special attention has been given to the structural, stoichiometric, and compositional flexibility of perovskite photocatalyst materials. The photocatalytic activity of perovskite materials in different photocatalysis applications is also discussed. Various mechanisms involved in photocatalysis application from wastewater treatment to hydrogen production are also provided. The key objective of this review is to encapsulate the role of perovskite materials in photocatalysis along with their fundamental properties to provide valuable insight for addressing future environmental challenges.
RESUMO
In this research work, BaCo0.4Fe0.4Zr0.2-x Ni x O3-δ (x = 0, 0.01, 0.02, 0.03, 0.04) perovskite cathode material for IT-SOFC is synthesized successfully using a combustion method and sintered at low temperature. The effects of nickel as a sintering aid on the properties of BaCo0.4Fe0.4Zr0.2O3-δ are investigated through different characterization methods. The addition of nickel increased the densification and grain growth at a lower sintering temperature 1200 °C. XRD analysis confirms a single phase of BaCo0.4Fe0.4Zr0.2O3-δ , and an increase in crystalline size is observed. SEM micrographs show formation of dense microstructure with increased nickel concentration. TGA analysis revealed that BaCo0.4Fe0.4Zr0.2-x Ni x cathode materials are thermally stable within the SOFC temperature range, and negligible weight loss of 2.3% is observed. The bonds of hydroxyl groups and metal oxides are confirmed for all samples through FTIR analysis. The highest electrical properties are observed for BaCo0.4Fe0.4Zr0.2-x Ni x (x = 0.04) due to increased densification and electronic defects compared to other compositions. The maximum power density of 0.47 W cm-2 is obtained for a cell having cathode material BaCo0.4Fe0.4Zr0.2-x Ni x (x = 0.02) owing to its permeable and well-connected structure compared to others.