Fuel Cells最新文献

Traditional automotive proton exchange membrane fuel cell (PEMFC) endurance testing relies on the fuel cell (FC) dynamic load cycle (FC-DLC) protocol, which inadequately reflects real-world driving conditions. To address this limitation the “Investigations on degradation mechanisms and Definition of protocols for PEM Fuel cells Accelerated Stress Testing” (ID-FAST) consortium defined the new representative “ID-FAST driving load cycle,” a novel approach capturing the load distribution, transitions, temperature variations, and humidity fluctuations experienced by FCs in real-world operation. We demonstrate the ID-FAST driving cycle itself and the integration into a realistic durability test program for FC test benches and present the resulting test data. Furthermore, we showcase its implementation within an accelerated stress testing (AST) protocol, highlighting its potential to significantly reduce testing time by accelerating degradation. Additionally, a novel method for highly dynamic humidity adjustment within test benches is introduced. By overcoming limitations of existing methods and incorporating the ID-FAST driving cycle, this work paves the way for a new era of efficient and realistic FC endurance testing, ultimately contributing to the development of more robust and durable automotive FC stacks.

The direct glycerol fuel cell (DGFC) is a promising application, although the catalyst has limits and could be improved. This study used density functional theory (DFT) calculations to elucidate how the addition of silver (Ag) to a palladium (Pd) catalyst can change the mechanism of the glycerol oxidation reaction (GEOR). It was discovered that the glycerol easily oxidized at the primary carbon at the start of the reaction. Glyceraldehyde and glyceric acid are produced as intermediary products due to primary carbon oxidation using Pd₃–Ag₁ (111). The addition of Ag aided C–C cleavage during the reaction, converting glyceric acid to glycolic acid rather than tartronic acid. The selectivity of high-value molecules such as glycolic and oxalic acid was more likely to increase due to the early C–C splitting. At the end of the possible chemical pathways, oxalic acid or formic acid can be generated with the nine electrons that can be transferred. This work's catalyst model and mechanism can be employed with a new alloy catalyst combination and modification or tested with a different type of alcohol or polyol as fuel. DFT analysis of the mechanism allows for more flexible improvement and design in the search for novel and better catalysts.

The porosity of the gas diffusion layer (GDL) significantly impacts the performance of proton exchange membrane fuel cells (PEMFCs). Assembly pressure in PEMFCs leads to GDL deformation and alterations in porosity distribution. This study integrated a three-dimensional (3D) GDL deformation model with a 3D two-phase PEMFC model, employing a four-term Fourier series model to optimize the fitting of the GDL porosity distribution curve. The approach quantitatively assessed the impact of GDL porosity distribution under assembly pressure on PEMFC performance. Results reveal an arched porosity distribution in GDL, peaking in the middle of low channels adjacent to ribs. High porosity enhances oxygen and heat conduction but excessive porosity may cause uneven current density distribution, hindering GDL drainage. Furthermore, the analysis compares performances at various GDL compression ratios and thicknesses, showing an initial rise then fall in current density with increasing pressure. This represents a trade-off between the adverse impact of GDL compression on mass transfer losses and the favorable impact of reduced ohmic losses. At the optimal pressure, the current density is 3% higher than neighboring values at the same potential, and within the optimal GDL thickness range, the current density error remains below 1%.

Algae–bacteria symbiosis (ABS) as a sustainable wastewater treatment process has drawn mounting attention. However, nontrivial CO₂ emissions were still present in municipal wastewater treatment due to the inadequate carbon fixation efficiency of microalgae under low carbon level. The obtained UV-induced mutant Chlorella vulgaris MIHL4 performed higher carbon fixation capability (14.5%) and biomass productivity (25.3%) with improved photosynthetic fluorescence parameters and enzyme activities compared to wild-type C. vulgaris. Transcriptome analyses showed pathways related to the carbon fixation and carbon catabolism were significantly up-regulated in MIHL4. Compared with ABS inoculated with wild-type C. vulgaris, CO₂ emissions were significantly reduced by 32.1%–38.3% in ABS inoculated with MIHL4, where the biomass growth, metabolic activity, and sludge granulation were enhanced. Chlorella responsible for carbon fixation was the dominant population (19.3%) in ABS inoculated with MIHL4, in which the abundance of functional microbes and genes associated with photosynthesis as well as nutrient removal increased.

Metal-based catalysts such as platinum and gold are frequently employed as electrocatalysts. However, they faced significant limitations, including high cost and susceptibility to poisoning and degradation, hindering their extensive utilization. To overcome these challenges, metal oxide offers promising alternatives for its fast electron transfer rate, large surface area, and high electrocatalytic activity in electrochemical oxidation materials. In this work, ZnO doped with Fe₂O₃ was scattered on reduced graphene oxide (rGO) to form a ZnOFe₂O₃/rGO hybrid by a hydrothermal method for glucose oxidation. The synthesized ZnOFe₂O₃/rGO composite was thoroughly characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS) analysis, and the electrochemical performance was evaluated using cyclic voltammetry. ZnO particles are highly uniform flowerlike particles interacting with uniform-size spherical-like particles of Fe₂O₃ in ZnO–Fe₂O₃ supported on the rGO. The result reveals that interaction between ZnO–Fe₂O₃ nanocomposites supported onto graphene sheets reduces agglomeration compared to parent nanoparticles. An increase in surface-to-volume ratio exhibits more surface-active sites for electrooxidation and thus improved catalytic performance by a negatively shifted potential of −36.62 mV versus Ag/AgCl, representing appropriate electrocatalysts for use as the anode in glucose fuel cells. The maximum current density of 0.5201 mA cm⁻² was achieved in the electrochemical glucose oxidation equipped with ZnOFe₂O₃/rGO, which was almost 20 and 3 times higher than ZnO and Fe₂O₃, respectively. The synergistic interaction of ZnO–Fe₂O₃ supported on rGO showed a vital role as an electrocatalytic mediator to facilitate the charge transfer for glucose oxidation.

The electrochemical operation of membrane electrode assemblies (MEAs) with different Nafion/C composition (0%, 20%, 30%, 40%, and 50%) and the same ultralow platinum load (0.02 mg_Pt cm⁻²) has been investigated. The electrodes were manufactured by depositing the catalytic ink, prepared with catalyst HiSPEC9100, onto the gas diffusion layers by wet powder spraying. MEA with 30% Nafion/C reached the highest power density (675 mW cm⁻²) and the lowest mass of Pt per power (0.059 g_Pt kW⁻¹) under H₂/O₂ 2 bar gauge pressure, the last quotient being 1.7 time less than USDRIVE objective for 2025. The electrochemical functioning of current membrane-electrode setups is compared with an analogous series with thicker electrode catalytic layer prepared with a commercial catalyst with a lower percent of Pt/C. Scanning electron microscopy characterization analysis of catalytic layers prepared by wet spraying exhibited an ionomer homogeneous network.

Hierarchically oriented macroporous NiO–BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY7) anode-supporting layer (ASL) was developed using the freeze casting technique. The resulting freeze-cast structure was analyzed through scanning electron microscopy and X-ray computed tomography. A thin layer of BZCY7 was utilized as a proton-conducting electrolyte, whereas La_1.9Sr_0.1Ni_0.7Cu_0.3O_3−δ –gadolinium-doped ceria 10% Gd (LSNC–GDC10) was employed and evaluated as cathode layer. The performance of the cell was assessed by means of electrochemical impedance spectroscopy and I–V–P curves at various temperatures. Furthermore, as a point of comparison, a cell with an ASL was prepared using the dry pressing method, incorporating 20 wt.% graphite as a pore-forming agent. The freeze-cast anode-supported cell demonstrated a polarization resistance of 1.45 Ω cm² at 550°C and 0.29 Ω cm² at 750°C. Maximum achieved power densities were 0.189 and 0.429 W cm⁻² at 550 and 750°C, respectively. For the cell fabricated by the dry pressing method, the maximum power densities were 0.158 and 0.397 W cm⁻² at 550 and 750°C, respectively. Additionally, the tortuosity factor of the anode layer and the gas diffusion streamline in the direction of solidification were determined by using 3D X-ray tomography imaging and subsequent image processing.