Search Results (376)

The sluggish kinetics of alkaline hydrogen oxidation reaction (HOR) and high cost of Pt–based catalysts have long hindered large–scale deployment of alkaline membrane fuel cells. Via first–principles calculations, we designed a series of 3d transition metal single atoms anchored on PdN₂ monolayer (TM–PdN₂, TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and evaluated their alkaline HOR performance. Ti-, Cr-, Fe-, Co-, Ni-modified systems exhibit excellent thermodynamic and electrochemical stability under operating conditions. Single-atom doping tunes the p-band center of N and d-band center of metal sites, enabling precise modulation of H and OH adsorption strengths. Mechanistic analysis reveals HOR follows H₂ + 2OH* → H* + OH* + H₂O → 2H₂O, with the final step as rate-determining step. H adsorption contributes 3.45 times more to HOR activity than OH adsorption. Fe–PdN₂ delivers the best performance, with an ultra–low barrier of 0.11 eV and a rate constant of 2.82 × 10¹⁰ s^–1·site⁻¹, values that significantly outperform those of Pt(111) (0.22 eV, 4.5 × 10⁹ s⁻¹·site⁻¹). This work provides theoretical guidance for rational design of high–performance alkaline HOR electrocatalysts. Full article

The development of sustainable electrocatalysts for clean energy by modifying biomass-derived activated carbon with nitrogen and transition metals is presented. Activated carbon (AWC) material was obtained using alder wood char as a precursor, while nitrogen and cobalt or copper nanoparticles were incorporated with the aim of creating efficient materials for hydrazine oxidation (HzOR) and direct hydrazine–hydrogen peroxide fuel cells (DHHPFC, N₂H₄–H₂O₂). The composition, structure, and surface morphology of the created materials were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The activity of the AWC, AWC–Co–N, and AWC–Cu–N catalysts for HzOR was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). N₂H₄–H₂O₂ fuel-cell tests were performed by applying the catalysts as both the anode and cathode. It was found that all materials retained a hierarchical porous carbon framework, while metal incorporation altered surface compactness. Cobalt doping produced well-dispersed Co nanoparticles and abundant Co–N–C coordination sites, whereas Cu introduction resulted in moderately compact structures with uniformly distributed Cu-based nanoparticles. Electrochemical measurements demonstrated that both metal dopants enhanced HzOR activity, with the catalytic performance following the order of AWC–Co–N > AWC–Cu–N > AWC. Fuel-cell testing further confirmed this trend: AWC–Co–N achieved the highest maximum power density (30.4 mW cm⁻²), outperforming AWC–Cu–N (17.7 mW cm⁻²). These results identify AWC–Co–N as a highly effective bifunctional electrocatalyst for DHHPFCs. Full article

Hydrogen peroxide fuel cells have emerged as a promising class of electrochemical energy conversion device owing to the dual redox character of H₂O₂, its liquid-phase storage, and its ability to operate in air-free environments. In this work, a dual-compartment direct H₂O₂ fuel cell using a Prussian Blue cathode and a tantalum anode, separated by a Nafion 115 proton exchange membrane, was systematically characterized and optimized with respect to electrolyte pH and ionic composition. The influence of pH on OCV was investigated independently in each compartment across the range of pH 2 to 12. In the tantalum compartment, OCV increased non-linearly with pH from 573 mV to 808 mV, driven by the enhanced electrochemical reactivity of the system under alkaline conditions. In the Prussian Blue compartment, OCV decreased from 676 mV to 199 mV with increasing pH, reflecting the instability of the material in alkaline conditions. The effect of the electrolyte ionic composition on average current density was subsequently investigated by varying the concentrations of NaCl and Dy(NO₃)₃. Increasing NaCl from 0 to 2.5 M produced an increase in current density from 0.414 mA/cm² to 0.973 mA/cm², consistent with ohmic resistance reduction through improved ionic conductivity. The addition of Dy(NO₃)₃ produced a positive response with an optimal concentration of $0.05$ M, at which current density reached 1.08 mA/cm², before declining sharply. Under the fully optimized conditions, pH 12 in the tantalum compartment, pH 2 in the Prussian Blue compartment, 0.3 M H₂O₂, 2.0 M NaCl, and 0.05 M Dy(NO₃)₃, the cell produced an OCV of 724 mV and a peak power density of 0.283 mW/cm² at a current density of 0.8 mA/cm². These results demonstrate that meaningful electrochemical performance can be achieved in a dual-compartment H₂O₂ fuel cell without the use of precious metal catalysts and highlight electrolyte engineering as an effective strategy for improving cell output in this class of device. Full article

Chromium-forming metallic interconnectors (ICs) are generally used to assemble protonic ceramic fuel cell stacks (PCFCs). Thus, Cr poisoning is a potential threat to the performance and stability of PCFCs. The effects of Cr deposit and poisoning on the performance and stability of a typical BaCo_0.8(Zr_0.8Y_0.2)_0.2O_3-δ (BCZY) air electrode after polarization with a current density of 0.2 A cm⁻² for 50 h are investigated. It is found that the BCZY and Cr₂O₃ powder are able to react even at 400 °C. In addition, Cr poisoning affects the chemical stability of BCZY. The humidification of air accelerates the Cr deposition and poisoning of BCZY by promoting the surface segregation of Ba and Cr evaporation from IC, and the main phase of the surface deposit is BaCrO₄. When the air humidity increases from 3% to 50%, the deposit layer depth increases from 0.949 μm to 2.870 μm. For the fuel cell exposed to air with a relative humidity of 3% and 50%, the polarization resistance (R_p) increases by 19.9% and 53.3%, while the ohmic resistance (R_Ω) increases by 3.5% and 17.1%, respectively. This study lays the foundation for further design of Cr-tolerant air electrodes and the selection of working conditions. Full article

Hydrogen (H₂) is a promising clean energy carrier with the potential to partially replace fossil fuels. Biological H₂ production using microorganisms offers an environmentally friendly alternative. The halotolerant cyanobacterium Aphanothece halophytica can produce H₂ under nitrogen-deprived and dark anaerobic conditions. In this study, a co-culture strategy was investigated to enhance H₂ production. Five bacterial strains were screened for their ability to improve H₂ production when co-cultivated with A. halophytica. Among them, Staphylococcus aureus significantly enhanced H₂ production, achieving a maximum rate of 11.11 ± 0.18 µmol H₂ g⁻¹ dry weight h⁻¹. Optimization of the bacterial partner revealed that S. aureus cells harvested at 12 h in the mid-logarithmic phase with an OD₆₀₀ of 4.0 were the most effective. An inoculum ratio of A. halophytica to S. aureus of 4:1 further enhanced H₂ production, increased bidirectional hydrogenase activity, and reduced O₂ accumulation. Under optimal conditions (0.945 mmol C-atom L⁻¹ glucose, 0.25 M NaCl, pH 7.4, and 35 °C), the maximum H₂ production rate reached 132.49 ± 4.45 µmol H₂ g⁻¹ dry weight h⁻¹, approximately 5.5-fold higher than that under normal conditions. The co-culture achieved a cumulative H₂ yield of 3248.51 ± 88.11 µmol H₂ g⁻¹ dry weight after 48 h. Full article

We report a straightforward and scalable strategy for the fabrication of three-dimensional Ni-rich bimetallic NiCu foam coatings on Ti substrates ((NiCu)_foam/Ti) via dynamic hydrogen bubble templating (DHBT) electrodeposition, followed by modification with an ultralow amount of Pt to construct an efficient ternary Ni–Cu–Pt catalytic system. The resulting foams exhibit highly porous dendritic architectures with interconnected channels, enabling a high density of electrochemically active sites and uniform metal distribution throughout the framework. Structural and compositional analyses (SEM–EDX) reveal a Ni-dominant composition (28.09–34.61 mg cm⁻²), with significantly lower Cu content (2.47–4.16 mg cm⁻²) and ultralow Pt loading (9.63–19.04 μg cm⁻²), maximizing catalytic efficiency while minimizing noble metal usage. Electrochemical studies in alkaline media demonstrate that the NiCu foam possesses intrinsic borohydride electrooxidation activity, which is substantially enhanced upon Pt incorporation, delivering a threefold increase in activity compared to the unmodified foam and outperforming bulk Pt. This improvement is attributed to the synergistic interplay within the Ni-rich ternary system, where trace Pt acts as a highly effective promoter. When implemented as anodes in NaBH₄–H₂O₂ fuel cells, Pt(NiCu)_foam/Ti achieves peak power densities of 239 and 301.6 mW cm⁻² at 25 °C and 55 °C, respectively. Overall, this study presents a cost-effective and scalable route to high-performance electrocatalysts for alkaline direct borohydride fuel cells, significantly reducing reliance on noble metals while maintaining superior activity. Full article

Metal ion-based chemo-immunotherapy is often limited by rigid intracellular metal homeostasis, insufficient reactive oxygen species (ROS) accumulation, and an immunosuppressive tumor microenvironment (TME). To overcome these limitations, we engineered an ATP-responsive, core–shell bimetallic nanoreactor (Cu/ZIF@PDA, termed CZP) featuring a precisely controlled ~25 nm biomimetic polydopamine (PDA) coating. Triggered by elevated tumoral ATP levels, CZP undergoes coordination-induced disassembly and promotes oxidative stress amplification. Specifically, the PDA shell acts as a superoxide dismutase (SOD) mimetic to continuously supply H₂O₂, fueling Cu²⁺-mediated Fenton-like reactions to unleash highly toxic hydroxyl radicals (•OH) while aggressively depleting the intracellular glutathione (GSH) pool. This irreversible oxidative damage, coupled with Zn²⁺-induced mitochondrial dysfunction, triggers profound mitochondrial DNA (mtDNA) leakage. Crucially, this cytosolic DNA robustly activates the cGAS-STING signaling axis, driving a massive surge in immunogenic cell death (ICD) and significantly promoting dendritic cell (DC) maturation. Furthermore, CZP markedly inhibited primary tumor growth in vivo and showed protection in a tumor re-challenge model, accompanied by enhanced dendritic cell maturation. These findings support the potential of this ATP-responsive bimetallic nanoplatform to promote antitumor immune activation. Full article

The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline media remain a primary bottleneck for anion exchange membrane fuel cells (AEMFCs), necessitating catalysts that synergistically optimize the adsorption of hydrogen (*H) and hydroxide (*OH) intermediates. Herein, we construct a well-defined heterointerface between Pd clusters and CeO₂ on nitrogen-doped carbon (Pd-CeO₂/NC) to electronically engineer the active sites. Spectroscopic studies and theoretical calculations collectively reveal that CeO₂ acts as an electron acceptor, drawing electrons from Pd via interfacial Pd-O-Ce bridges. This charge transfer induces a downshift of the Pd d-band center, which optimally tunes the adsorption strength of both *H and *OH at the interface, thereby breaking the scaling relationship that limits HOR activity. The resulting Pd-CeO₂/NC catalyst achieves an exceptional exchange current density of 3.66 mA cm⁻², surpassing that of commercial Pt/C by a factor of two and ranking among the best reported noble metal catalysts. Furthermore, it exhibits outstanding long-term stability and remarkable CO tolerance, retaining high activity in an atmosphere containing 1000 ppm CO. This work underscores the profound efficacy of metal–oxide heterointerface engineering in regulating electronic structures for multi-intermediate optimization, offering a viable design principle for advanced alkaline HOR electrocatalysts. Full article

To optimize the oxygen reduction reaction activity and long-term stability of the PrBaFe₂O_6-δ (PBF) cathode for protonic ceramic fuel cell (PCFC), this study employed the sol–gel method to dope Sc at the Fe-site of PBF, preparing a novel PrBaFe_1.8Sc_0.2O_6-δ (PBFS) cathode. The effects of different sintering temperatures on the phase composition, microstructure, and electrochemical performance of the PBFS cathode were systematically studied. Results showed that the PBFS cathode sintered at 1000 °C formed a single cubic perovskite structure, exhibiting excellent chemical compatibility with the electrolyte. Sc doping induced Fe in the cathode to exhibit a mixed valence state of Fe²⁺/Fe³⁺/Fe⁴⁺, thus significantly increasing the oxygen vacancy concentration. The single cell assembled achieved a peak power density of 1.303 W·cm⁻² and a polarization resistance as low as 0.035 Ω·cm² with H₂ as the fuel at 700 °C. Moreover, after 100 h of long-term operation at 650 °C, the power density decayed by only 5.23%, thus demonstrating excellent long-term stability. This study offers an efficient cobalt-free cathode candidate for PCFC. Full article

The increasing integration of renewable energy sources increases the variability and uncertainty of power systems, requiring advanced prediction-based control strategies. This paper proposes an integrated AutoML–MPC framework for a hybrid renewable energy system (HRES) combining solar and wind generation, biomass, battery energy storage, and a hydrogen chain (electrolyzer and fuel cell). Short-term load and generation forecasts are made using H2O AutoML models, and the energy flow allocation is optimized using model-based control (MPC) formalized in the form of mixed-integer linear programming (MILP). The objective function minimizes electricity imports from the grid and the associated ${\mathrm{C}\mathrm{O}}_2$ emissions, subject to technological constraints. The results obtained showed a clear distribution of short-term (battery) and long-term (hydrogen) storage functions in time: during periods of excess generation, the electrolyzer operated close to nominal mode, and in the deficit phase, the fuel cell was activated, reducing the need for grid imports. The battery ensured fast short-term balancing, while the hydrogen system compensated for the longer-term energy shortage. The forecast models were characterized by high accuracy ($R^2>0.98$), which allowed for reliable planning of energy flows over the MPC horizon. The proposed methodology allows for effective coordination of storage technologies of different time scales, maximum use of renewable generation and reducing the system’s dependence on the external grid. Full article

We engineered a compact methanol steam reforming (MSR) system tailored to power a 1 kW High-Temperature Proton Exchange Membrane (HT-PEM) fuel cell. The unit integrates an evaporator, reformer, and burner within a cylindrical titanium-alloy vacuum flask to minimize parasitic heat loss. Guided by an Artificial Intelligence Complex System Response (AICSR) framework, we developed a segmented catalyst architecture that positions an optimized Pd/ZnO/Al₂O₃ catalyst downstream of a commercial Cu–Zn catalyst bed. This spatial configuration reduces palladium consumption by >50% while maintaining a hydrogen generation rate of 8000 sccm at 250 °C. During a 40 h stability test, the system exhibited a low deactivation rate of 0.235% h⁻¹, with methanol conversion decaying gradually from 98.1% to 88.7%. The downstream PdZn intermetallic phase actively promoted the water–gas shift (WGS) reaction, restricting CO concentration to an average of 3.9% (minimum 2.5%). Achieving a system thermal efficiency of 88.589% and a 20 min startup time, this design validates AI-assisted spatial catalyst distribution as a highly viable strategy for compact hydrogen generation. Full article

Trace amounts of CO in H₂-rich gas can poison Pt electrodes in proton-exchange-membrane fuel cells, necessitating selective CO removal. Preferential oxidation of CO (PROX) offers an efficient route to oxidize CO while preserving H₂. Although noble-metal-based catalysts are widely used, their high cost has driven interest in non-precious alternatives. Co₃O₄–CeO₂ catalysts have emerged as particularly promising due to their high activity and stability. Two series of Co–Ce/SiO₂ catalysts were prepared via impregnation: in the first, Ce was introduced and calcined prior to Co deposition; in the second, Co and Ce nitrates were co-deposited from a mixed aqueous solution. The latter method enhances the interaction between Co₃O₄ and CeO₂, increasing the availability of surface oxygen species. Stability tests on the most active sample demonstrated remarkable durability, maintaining near-complete CO conversion over 100 h on dry stream. Full article

This work presents the development and validation of a 1D finite-volume model for the simulation of planar solid oxide cells (SOCs), developed for integration in more complex systems and process simulations. The model allows to investigate the temperature, composition, and current density profiles along the channel. In this work, the Fick’s equations typically used to calculate the concentration overpotential due to H₂ and H₂O diffusion in the electrode are improved compared to 1D SOC models available in the literature. In particular, the approximate analytical solution of the dusty gas model (DGM) equations allows for a better definition of H₂ and H₂O mixture diffusion coefficients, which are relevant, for instance, in the case of solid oxide fuel cells (SOFCs) fed with reformate gas mixtures. Differently from other 1D models available in the literature, the model developed is validated using experimental SOFC polarization curves covering a wide range of operating conditions in terms of molar fraction of H₂ (21–93%) and H₂O (7–50%) in the fuel, temperature (550–750 °C), and fuel utilization factor (exceeding 90%), demonstrating that 1D SOC models retain a good description of the physical processes occurring within the cell. While this work focuses on a co-flow SOFC configuration, the model can simulate a counter-flow configuration and electrolysis operation without modifying the model equations. Full article

Electrode degradation represents a primary factor contributing to the performance decay. The composition design of electrode materials directly determines the long-term stability of solid oxide fuel cell (SOFC) under high-temperature service conditions. This paper focuses on the effect of anode and cathode material compositions on the creep damage and failure probability of SOFCs after 50,000 h creep. The results reveal an optimal Ni content range for mechanical integrity. Specifically, increasing the Ni volume fraction from 30% to 50% results in a reduction in the creep damage. In contrast, extending the increase to 60–70% causes a general reversal of this trend, with the creep damage showing an overall increase. The paper concludes that the Ni volume fraction of 50–60% is appropriate to maintain the long-term operation of SOFC. The La_0.8Sr_0.2MnO₃ (LSM) volume fraction with higher electrochemical efficiency can be selected for cathode manufacturing. This study provides a reference for developing long-life SOFC electrode materials. Full article

This study evaluated the feasibility of using effluent from the anodic chamber of a microbial fuel cell (MFC), powered by real fruit and vegetable wastewater, as a cultivation medium for Tetraselmis subcordiformis, a microalga capable of bio-photolytic hydrogen production. In three experimental variants, different organic loading rates were applied in the anodic chamber, resulting in significant differences in effluent quality and its suitability as a culture medium. In contrast to the dominant MFC configurations, in which microalgae act as cathodic biocatalysts, the microbial fuel cell in this study was used as a source of the inevitable anode effluent, which was subsequently valorized as a cultivation medium for the marine microalga T. subcordiformis to support biomass and hydrogen production. In variants with moderate COD concentration and low lipid content, the highest biomass concentrations, ranging from 941 ± 104 mg VS/L to 1020 ± 108 mg VS/L, were obtained, along with the highest nitrogen assimilation efficiency (48.7–49.1%) and phosphorus assimilation efficiency (62.3–63.1%). The variant in which the culture medium contained the highest concentrations of COD, TSS, and lipids showed a substantial limitation of biomass growth to 745 ± 75 mg VS/L and lower nutrient removal efficiency (total nitrogen—42.3 ± 4.7%, total phosphorus—55.0 ± 5.0%). The obtained biomass was then used for H₂ production in a mineral photobiolytic medium. The highest total hydrogen production reached 184.7 ± 25.0 mL, while the specific hydrogen yield reached 193.7 ± 32.6 mL/g VS. Increased concentration of organic matter in the medium reduced total hydrogen production to 112.0 ± 14.8 mL, mainly due to lower biomass concentration, although the specific hydrogen yield remained high (153.4 ± 25.8 mL/g VS). The biogas composition was stable (H₂ 58.0–58.7%, CO₂ 35.3–35.9%, O₂ 6.0–6.2%). Full article