Metal-supported solid oxide fuel cells (MS-SOFCs) represent a promising advancement for intermediate-temperature energy conversion applications due to their enhanced mechanical robustness and rapid startup capabilities. This investigation systematically evaluates the correlation between yttria-stabilized zirconia (8YSZ) electrolyte thickness and electrochemical performance in NiFe-supported architectures. Three distinct cells featuring YSZ electrolyte thicknesses of 7.05, 14.2, and 21.2 μm were fabricated via tape casting and co-sintering at 1,350 °C, while maintaining identical NiFe support (280 μm) and Ni-YSZ anode (22 μm) thicknesses. Electrochemical characterizations revealed a clear inverse relationship between electrolyte thickness and cell performance. The cell with the thinnest electrolyte (7.05 μm) achieved the highest power density of 0.32 W/cm2 at 800 °C, representing a 4.6-fold improvement compared to the thickest variant (21.2 μm). Electrochemical impedance spectroscopy and distribution of relaxation times analysis confirmed that ohmic resistance dominated the total cell impedance, and scaled linearly with electrolyte thickness, while electrode kinetics remained consistent. This study establishes that thin YSZ electrolytes (≤ 8 μm) prepared via co-sintering fabrication maximize MS-SOFC performance while maintaining structural integrity, providing an essential design for high-performance metal-supported fuel cell development.
Sn-doped In2O3 (ITO) thin films were deposited on bare glass and on glass with a SiO2 buffer layer using radio frequency magnetron sputtering at room temperature, and the structural, electrical, and optical properties of the films were considered according to changes in the thickness of the upper ITO film and the lower SiO2 buffer layer. While the 100 nm-thick ITO monolayer film showed a visible transmittance of 80.52 % and an electrical resistivity of 2.0 × 10-3 Ωcm, the ITO 70 nm/SiO2 30 nm double layered film showed an increased visible transmittance of 83.38 % and a decreased electrical resistivity of 1.3 × 10-3 Ωcm. Also, since the surface roughness of the ITO 70 nm/SiO2 30 nm films (1.66 nm) was lower than that of the ITO films (2.31 nm), it was concluded that having an effective thickness of SiO2 buffer layer can improve the flatness of the ITO/SiO2 thin film. In addition, the work function of the ITO/SiO2 film is influenced by the SiO2 buffer layer, and it has been shown that the work function of the ITO/SiO2 film (4.63 eV) is higher than that of ITO single layer film. Comparing optical transparency and electrical resistivity in this study, the ITO 70 nm/SiO2 30 nm films showed a relatively better electro-optical performance index (figure of merit) than the ITO 100 nm monolayer thin film.
To satisfy the ever-increasing demand for high-energy density and cycle stability in electric double-layer capacitors, research on conductive additives for electric double-layer capacitors has been conducted, mainly by focusing on shape or network formation using a 1D/2D structure or composite strategy. The conductive additive for electric double-layer capacitors needs to have a structure that not only improves electrical conductivity, but also forms an electron transfer path between the active materials and maintains accessibility to electrolyte ions. This study proposes a novel strategy to improve electron transfer and ion migration by simultaneously controlling the conductivity, surface chemistry, and hierarchical pore structure of ZIF-67-derived porous carbon. The graphitic carbon framework structure and micro/meso/macro pore structure of the ZIF-67-derived porous carbon can be simultaneously optimized by controlling carbonization temperature. The resulting graphitic carbon framework formed an excellent electron transfer network, and the optimized pore structure contributed to improved accessibility and diffusion path for electrolyte ions. As a conductive additive in an electrode, the optimal structure 600-PC was able to maintain an ion transfer path while forming a continuous electron transfer network. 600-PC exhibited superior electrochemical performance with a specific capacitance of 121.4 F/g, energy density of 16.86 Wh/kg (400 W/kg), and 15.27 Wh/kg (4,000 W/kg) as a conductive additive in an electric double-layer capacitor.
Bismuth vanadate (BiVO4) has been widely investigated as a photoanode material for photoelectrochemical (PEC) water splitting because it has a suitable bandgap and strong visible-light absorption. However, its performance is highly dependent on film thickness, as there is a trade-off between light absorption and charge transport. In this study, BiVO4 thin films with thicknesses of 200, 300, and 400 nm were deposited on FTO substrates via RF magnetron sputtering to systematically investigate the thickness-dependent PEC performance. X-ray diffraction and field-emission scanning electron microscopy confirmed the formation of uniform and crystalline BiVO4 thin films. UV–vis spectroscopy revealed that light absorption increased with film thickness. PEC measurements showed that the 300 nm BiVO4 photoanode delivered the highest photocurrent density of 1.91 mA cm-2 at 1.23 V vs. RHE, along with a maximum HC-STH efficiency of 0.309 %. Electrochemical impedance spectroscopy indicated that the 300 nm film exhibited the lowest charge transfer resistance, suggesting reduced charge recombination. Furthermore, the optimized photoanode maintained stable photocurrent for over 5 hours. These results highlight that precise thickness control via RF magnetron sputtering is critical for optimizing the PEC performance of BiVO4 photoanodes.
This study investigated the hydrogen embrittlement behavior of 316 austenitic stainless steel subjected to hydrogen charging at different temperatures, using slow strain-rate testing and acoustic emission (AE) techniques. Compared to the noncharged specimen, the specimen H-charged at 25 °C exhibited similar elongation and a ductile fracture mode, while hydrogen charging at 60 °C led to a pronounced reduction in elongation accompanied by quasi-cleavage fracture. This degradation may be associated with enhanced hydrogen transport and redistribution at the elevated charging temperature, which could increase the effective hydrogen activity at microstructural sites, known to be critical to crack initiation and propagation. Feritscope measurements indicated a relative increase in strain-induced martensite formation in the hydrogen-charged specimens. Specifically, the H-charged at 25 °C specimen showed a localized increase in martensite near the fracture surface, and the H-charged at 60 °C specimen exhibited a high martensite fraction over the measured region of the gauge section. AE analysis showed that the cumulative number of AE events decreased after hydrogen charging, while the cumulative absolute energy increased, particularly for the H-charged at 60 °C specimen. These results suggest a relative change in fracture behavior under hydrogen-charged conditions, from ductile fracture involving numerous low-energy AE events to more abrupt fracture behavior characterized by fewer but more energetic AE events. This study suggests that AE analysis can serve as a complementary tool for characterizing deformation and the fracture behavior associated with hydrogen embrittlement in austenitic stainless steels.