Low electrode impedance paired with low catalyst loading in intermediate and low temperature fuel cells is extremely difficult to achieve, posing a major obstacle to commercialization. Here we demonstrate a scalable and facile route to obtain nanostructured composite solid acid fuel cell electrodes consisting of Pt decorated carbon nanotubes and CsH₂PO₄ microparticles as the electrolyte. Electrochemical impedance measurements in humidified hydrogen at 240 °C show very low 0.05 Ω cm² area normalized electrode resistance, with a Pt loading of only 0.41 mg_Pt cm⁻². This is a reduction of the Pt loading by more than one order of magnitude paired with even lower electrode impedance values compared to the current state-of-the-art in literature. Fuel-cell measurements show remarkably stable electrode performance over a 17 h period with a final degradation rate of 0.1% h⁻¹.

Spray drying was explored as a new CsH ₂ PO ₄ nanoparticle synthesis method and a systematic parameter study was conducted to discover the set for high deposition rate and small particle sizes for solid acid fuel cell electrodes.

Acid resistance of CAD/CAM resin composites. Erosion-related tooth surface loss is closely related to acid exposure, such as contact with acidic beverages or disease-related reflux. As a result, dental restorations in affected patients are also exposed to acids, which indicates that the performance and longevity of a dental restoration is impacted by the acid resistance of the individually employed restorative materials. However, unlike for ceramic materials, the acid resistance of CAD/CAM resin composites is not commonly evaluated by the manufacturers, and no standardised test methods have yet been established. Against this background, the present in vitro study aimed to examine the long-term resistance of CAD/CAM resin composites (Brilliant Crios, Cerasmart, Grandio blocs, Lava Ultimate, Shofu Block HC) against three acidic media (tonic water, acetic acid, hydrochloric acid) as well as demineralized water and to investigate potential damage mechanisms. Changes in surface roughness (Sa) were detected by confocal laser scanning microscopy (CLSM), and changes in surface hardness were measured using Vickers hardness (HV). The damage mechanisms were analysed by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and micro X-ray computer tomography (µXCT). For each material, few changes in either Sa or HV were identified for at least one of the different media; for Cerasmart, the sharpest deterioration in surface properties was observed. SEM–EDS revealed leaching of barium, aluminium, and titanium from fillers in a 2 µm zone on the rough but not on the polished surface of the specimen. Within the limitations of the current study, it can be concluded that polished CAD/CAM resin composites can be recommended for clinical use in patients with erosive conditions.

In the study the influence of different dental technical tools on the surface temperature and phase composition of fixed dental prostheses (FDPs) made of yttria-partially stabilized zirconia polycrystals (3Y-/4Y-/5Y-PSZ) was investigated. FDPs were fabricated by using computer-aided manufacturing (CAM). The FDPs were treated with a contra-angle handpiece equipped with different burs and polishers. The resulting surface temperatures were measured with a thermographic camera, and the resulting phase transformations were investigated by X-ray diffraction and quantified by Rietveld refinement. Processing with burs resulted in no phase transformation, but a preferred orientation shift. Using coarse polisher induced a phase transformation to the rhombohedral phase, while fine polishers produced no relevant phase transformations and no preferred orientation shift. Compared to the monoclinic phase (ca. 9% theoretical volume increase), which is associated with low-temperature degradation (LTD), the rhombohedral phase is much more voluminous (ca. 15% theoretical volume increase) and distorted and, therefore, has a greater degradation potential.

Electrodes are currently the primary performance-limiting component in low and intermediate temperature fuel cells. A proven method for improving electrode performance in solid acid fuel cells is to create ever finer nanostructures and thus increase the electrochemically-active surface area. However, this performance enhancement is limited by issues of long-term stability, as well as increasing both the electronic and ionic conduction pathways. Here, we combine a systematic experimental study with a computational model to quantify the effect of (1) the stabilizing polymer polyvinylpyrrolidone as well as (2) the porosity and electrode layer thickness on the average ionic conductivity of the solid acid electrolyte CsH₂PO₄ in a composite solid acid fuel cell electrode. With a multiscale simulation approach using a combined molecular dynamics and lattice Monte Carlo method, proton conduction through a porous electrode is simulated at mesoscopic timescales while retaining near-atomistic structured evolution. Electrochemical impedance spectroscopy is used to evaluate the porous electrodes obtained via spray drying. Both approaches reveal a similar and significant contribution of the porous electrolyte layer to the overall cell resistance. This indicates that geometrical parameters, as well as stabilizing materials may play an essential role when designing a high-performance solid acid fuel cell.