A cost-effective activation method was developed to enhance the performance of commercial stainless steel (SS) as a bifunctional electrocatalyst for the AEM water electrolyzer, exhibiting remarkable durability at 5.0 A (1.0 A cm⁻²) for 250 h.

Vanadium dioxide (VO₂) is a well-known thermochromic material that can potentially be used as a smart coating on glazing systems in order to regulate the internal temperature of buildings. Most growth techniques for VO₂ demand high temperatures (>250 °C), making it impossible to comply with flexible (polymeric) substrates. To overcome this problem, hydrothermally synthesized VO₂ particles may be dispersed in an appropriate matrix, leading to a thermochromic coating that can be applied on a substrate at a low temperature (<100 °C). In this work, we reported on the thermochromic properties of a VO₂/Poly-Vinyl-Pyrrolidone (PVP) nanocomposite. More specifically, a fixed amount of VO₂ particles was dispersed in different PVP quantities forming hybrids of various VO₂/PVP molar ratios which were deposited as films on fused silica glass substrates by utilizing the drop-casting method. The crystallite size was calculated and found to be 35 nm, almost independent of the PVP concentration. As far as the thermochromic characteristics are concerned, the molar ratio of the VO₂/PVP nanocomposite producing VO₂ films with the optimum thermochromic properties was 0.8. These films exhibited integral solar transmittance modulation (overall wavelengths) ΔTr_sol = 0.35%–1.7%, infrared (IR) switching at 2000 nm ΔTr_IR = 10%, visible transmittance at 550 nm Tr_Vis = 38%, critical transition temperature T_C = 66.8 °C, and width of transmittance hysteresis loop ΔT_C = 6.8 °C. Moreover, the critical transition temperature was observed to slightly shift depending on the VO₂/PVP molar ratio.

In the present work, symmetrical oxide ion conducting solid oxide single cells with inkjet-printed composite LSM-YSZ electrodes, onto commercially available YSZ dense substrates using GDC as buffer interlayer, were fabricated and characterized. Stable inkjet-printable LSM-YSZ nanoparticle inks were developed based on water solvent, after processing with high intensity ball milling. The deposition of LSM-YSZ electrodes was performed by inkjet printing, as well as a conventional additive manufacturing technique, screen printing, in order to compare the electrochemical performance of the produced cells for the reversible charge transfer reaction (O₂ + 4 e^- ↔ 2 O^2-). The physicochemical properties of the LSM-YSZ nanoparticle ink was investigated to determine ink printability. The electrochemical performance of fabricated inkjet-printed and screen printed symmetrical cells (LSM-YSZ | GDC | YSZ | GDC | LSM-YSZ) exposed under a synthetic air atmosphere was evaluated in a single chamber cell reactor, employing the AC impedance spectroscopy and linear scan voltammetry techniques, at the temperature range of 700-850 °C. The inkjet-printed electrodes exhibited highly homogeneous and porous morphologies with the corresponding cell achieving current densities almost five times higher, up to 1 A/cm² at 2 V cell potential and 850 °C, than those of the equivalent screen-printed one. To the best of our knowledge, this is the first successful implementation of water-based inks of LSM-YSZ electrodes in the fabrication of inkjet-printed solid oxide cells.

In the present work, the individual or synergistic effect of Ni-based catalysts (Ni/CeO₂, Ni/Al₂O₃) and an eutectic carbonate salt mixture (MS) on the CO₂ gasification performance of olive kernels was investigated. It was found that the Ni/CeO₂ catalyst presented a relatively superior instant gasification reaction rate (Rco) compared to Ni/Al₂O₃, in line with the significant redox capability of CeO₂. On the other hand, the use of the binary eutectic carbonate salt mixture (MS) lowered the onset and maximum CO₂ gasification temperatures, resulting in a notably higher carbon conversion efficiency (81%) compared to the individual Ni-based catalysts and non-catalytic gasification tests (60%). Interestingly, a synergetic catalyst-carbonate salt mixture effect was revealed in the low and intermediate CO₂ gasification temperature regimes, boosting the instant gasification reaction rate (Rco). In fact, in the temperature range of 300 to 550 °C, the maximum Rco value for both MS-Ni/Al₂O₃ and MS-Ni/CeO₂ systems were four times higher (4 × 10⁻³ min⁻¹ at 460 °C) compared to the individual counterparts. The present results demonstrated for the first time the combined effect of two different Ni-based catalysts and an eutectic carbonate salt mixture towards enhancing the CO production rate during CO₂ gasification of olive kernel biomass fuel, especially in the devolatilization and tar cracking/reforming zones. On the basis of a systematic characterization study and lab-scale gasification experiments, the beneficial role of catalysts and molten carbonate salts on the gasification process was revealed, which can be ascribed to the catalytic activity as well as the improved mass and heat transport properties offered by the molten carbonate salts.