Proton-conducting ceramic fuel cells (PCFCs) fueled directly by ammonia have demonstrated remarkable advantages as a promising clean energy technology. However, conventional nickel-based cermet anodes in direct ammonia PCFCs (DA-PCFCs) exhibit insufficient catalytic activity and poor thermal stability for ammonia decomposition, leading to suboptimal electrochemical performance and shortened operational lifetime. In this study, an efficient ammonia decomposition catalyst (Ce0.9Gd0.1)0.9Ni0.05Fe0.05O2-delta (CGNF) with in-situ exsolved FeNi3 nanoparticles is investigated as an advanced anode catalytic layer (ACL) in DA-PCFCs. The results show that DA-PCFCs with CGNF ACL show excellent peak power densities of 1.010 W & sdot;cm-2 and can operate over 140 h at 600 degrees C with negligible degradation. In-situ exsolved FeNi3 together with CGNF can efficiently promote ammonia decomposition thus improve the electrochemical performance and long-term stability of DA-PCFCs. This work presents a practical and effective anode catalytic layer design strategy for DA-PCFCs.

Nickel foam is commonly employed as a hydrogen electrode current collector in solid oxide cells, thanks to its dual role in gas diffusion and current conduction. The effect of nickel foam structure was investigated to enhance the water vapour transport and the electrochemical performance of solid oxide electrolysis cells. As the compression residual (CR) of the nickel foam increases, the planar pore size increases until the nickel mesh ruptures at its tensile limit. Excellent performance in contact resistance and gas pressure regulation is observed at a CR of 0.4 and a pores per inch (PPI) of 90. The introduction of the overlap structure enhances water vapour pressure and nickel mesh contact density, consequently reducing both ohmic and polarization resistances. As a result, a single cell employing the modified nickel foam demonstrates a low degradation rate of 3 % kh-1 over 200 h at 0.550 A cm-2 , indicating excellent long-term operational stability.

A reversible solid oxide cell (RSOC) can generate electricity and hydrogen, respectively, when operating in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes. However, at high current densities, serious Sr segregation in the traditional La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd0.1Ce0.9O2-δ (LSCF-GDC) oxygen electrode leads to a decrease in the catalytic activity of the cathode and consequently poor performance stability of RSOC. In this work, Ca doping was proposed to suppress Sr segregation in the LSCF-based composite electrodes. The smaller radius of the Ca atom could reduce the elastic driving force of Sr segregation, while the reasonable Ca-doping concentration could alleviate the steep oxygen vacancy gradient formed under high current density and thereby reduce the electrostatic driving force of Sr segregation. Consequently, after appropriate Ca substitution at the A-site, the prepared La0.6Sr0.2Ca0.2Co0.2Fe0.8O3-δ-Gd0.1Ce0.9O2-δ(LSCCF-GDC) oxygen electrode reported significantly enhanced stability during long-term operation at high current density. At 750 °C and a current density of 1.2 A·cm-2, the degradation rates of the cell with LSCCF-based composite oxygen electrode were 10 mV/100 h in SOFC mode and 17 mV/100 h in SOEC mode, which was much lower compared with the corresponding values of the cell with the traditional LSCF-based composite oxygen electrode (18 mV/100 h in SOFC mode and 82 mV/100 h in SOEC mode).

Reversible proton ceramic cells (R-PCCs) as highly efficient energy conversion devices can operate at intermediate to low temperatures (400-700 degrees C). However, the lack of high-performance air electrodes with excellent oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) performance has hindered the development of R-PCCs. In this work, we investigate a face-sharing hexagonal structure perovskite BaCo0.6Fe0.4O3-delta (BCF64) as a highly electrocatalytic air electrode for R-PCCs. The results show that the R-PCCs with the BCF64 air electrode can achieve an impressive peak power density of 1.094 W cm-2 in fuel cell mode and a current density of -2.584 A cm-2 at 1.3 V in electrolysis mode at 600 degrees C. Furthermore, the cells demonstrate excellent stability, achieving 300 h of reversible cycling at 600 degrees C in dual-mode alternative operation and stable operation for 300 h in individual electrolysis and fuel cell modes, respectively. The density functional theory (DFT) calculations reveal that the face-sharing hexagonal BaCo0.6Fe0.4O3-delta (BCF64) is conducive to decreasing the formation energy of oxygen vacancies and the proton migration energy barrier within the perovskite, thereby enhancing the electrocatalytic performance for ORR/OER processes.

To fulfill the real-time monitoring requirements for the high SO2 concentrations in industrial emissions, yttria-stabilized zirconia (YSZ)-based mixed-potential SO2 sensors with rare-earth vanadates (AVO(4), A = Ce, Sm) as sensing electrode materials were investigated in this work. The microstructure of the AVO(4) electrode was tuned by adjusting the corresponding sintering temperature (800-1100 degrees C), reaching the optimal match between particle size and pore structure at 1000 degrees C. The CeVO4 sensor sintered at 1000 degrees C exhibited the best performance at the operation temperature of 400 degrees C, in which its polyhedral structure and the formation of CeVO4/CeO2 heterointerfaces enhanced the diffusion and adsorption of SO2, achieving a response of -69.73 mV for 500 ppm SO2 and a sensitivity of -25.92 mV/decade for 50-500 ppm SO2, significantly higher than that of the SmVO4 electrode (-18.87 mV, -12.81 mV/decade). Additionally, the sensor can be operated at a wide temperature range from 400 degrees C to 600 degrees C. The response/recovery times were significantly shortened to 31 s/45 s (100 ppm) and 11 s/33 s (500 ppm) at 600 degrees C, approximately 90 % faster than those of 400 degrees C, while maintaining a sensitivity of -13.06 mV/decade for 50-500 ppm SO2. Furthermore, the sensor exhibited excellent repeatability and long-term stability at 600 degrees C, which remained stable for 18 days with a slight response variation of <8 %. This study provides novel material design and optimization strategies for developing high-sensitivity SO2 sensors with a wide detection range and rapid response ability, which are capable of operating under harsh industrial conditions.

As an efficient device for energy conversion, solid oxide electrolysis cells (SOECs) can utilize renewable energy to efficiently convert CO2 into CO, realizing both CO2 resource utilization and chemical storage of renewable energy. Traditional nickel-yttria-stabilized-zirconia (Ni-YSZ) fuel electrodes face issues such as Ni agglomeration and carbon deposition in practical applications. In this study, a pure ceramic fuel electrode of fluorine and gadolinium co-doped CeO2 with mixed ionic-electronic conducting and enhanced electrocatalytic activity is investigated. The results reveal that F and Gd co-doped CeO2 exhibits enhanced catalytic activity and CO2 adsorption capacity. The cell with the F0.1Gd0.1Ce0.9O2-delta fuel electrode can achieve a maximum electrolysis current density of 1.45 A cm-2 at 1.5 V at 850 degrees C, with an Rp of 0.023 Omega cm2. Furthermore, the cell exhibits excellent durability for 200 h at 0.5 A cm-2 without significant degradation. This work shows that F and Gd co-doped CeO2 provides a feasible way for the development of nickel-free SOEC cathodes.

Reversible proton ceramic cells (R-PCCs) are attracting increasing attention as sustainable electrochemical devices that can switch between efficient power generation and steam electrolysis. However, their development is limited by the scarcity of air electrodes that can offer both fast oxygen/water conversion kinetics and robust structural stability. Herein, we introduce a high-entropy composite air electrode that has been designed using an entropy-driven dual-phase exsolution approach and formulated as xNiO-yCeO(2)-Pr0.2La0.2Ba0.2Sr0.2Ca0.2Fe0.2Ni0.15-xCe0.05-yO3-delta (N/C-XFNC). The configurationally disordered perovskite matrix provides enhanced thermodynamic stability, while the in situ exsolution of NiO and CeO2 nanoparticles creates bifunctional catalytic sites. NiO promotes oxygen adsorption and dissociation, while CeO2 substantially strengthens water uptake and proton hydration. Combined experimental characterization and first-principles analysis reveal that R-PCCs equipped with the N/C-XFNC electrode deliver markedly improved performance. It achieves a peak power density of 1.41 W cm(-2) and a current density of -2.61 A cm(-2) at 1.3 V in electrolysis mode at 650 degrees C. Furthermore, the cells further sustain stable operation for over 800 h at 600 degrees C, highlighting the structural resilience of the high-entropy architecture. This work presents a generalizable design concept that leverages entropy engineering and controlled exsolution to create durable, high-performance air electrodes for next-generation R-PCCs technologies.

The advancement of proton-conducting solid oxide cells (P-SOCs) for next-generation energy conversion is currently impeded by the lack of oxygen electrodes that combine high proton conductivity with rapid catalytic kinetics at intermediate temperatures. Herein, we present a novel Co-based oxide (Ca0.8Pr0.2Co0.8Fe0.2O3–δ, CPCF) featuring an in-situ self-assembled “perovskite-brownmillerite” biphasic heterostructure designed as a high-performance triple-conducting oxygen electrode. This tailored architecture leverages a synergistic mechanism wherein the Brownmillerite phase provides ordered oxygen vacancy channels for accelerated bulk ionic transport, while the Perovskite phase sustains a percolating electronic network. Notably, CPCF displays a marked “hydration-induced conductivity enhancement”, indicative of substantial proton uptake capacity, which effectively expands the electrochemically active zone across the entire electrode bulk. As a result, CPCF-based single cells deliver exceptional reversible performance at 700 °C, yielding a peak power density of 1.01 W/cm2 in fuel cell mode and a current density of –3.30 A/cm2 (at 1.3 V) in electrolysis mode, alongside robust durability over 150-hour operation. These findings demonstrate that regulating defect chemistry and ion transport kinetics through hetero-interface engineering offers a viable pathway for the rational design of superior P-SOC oxygen electrodes.

This study addresses key challenges in one-step cosintering fabrication of asymmetric Fe-Cr alloy-supported solid oxide fuel cells (SOFCs), focusing on the link between processing limitations and the lower performance of this cell type relative to other metal-supported SOFCs. Cells fabricated via one-step cosintering under ultralow PO2 exhibit good electrolyte integrity with an open-circuit voltage of 1.16 V and good performance during short-term testing. The resulting peak power densities of 224 and 568 mW cm(-2) are consistent with values reported for sintered asymmetric Fe-Cr supported SOFCs, thereby validating the viability of the one-step approach. Critical analysis of the structure-performance relationship identifies the relatively thick electrolyte and the absence of an optimized anode functional layer as the primary constraints on the electrochemical output. By establishing a processing and performance baseline, this work demonstrates effective defect control and identifies optimization strategies, including anode and cathode engineering, to overcome current performance bottlenecks. [GRAPHICS]

The anode support microstructure is crucial for mass transport and electrochemical reactions in solid oxide fuel cells (SOFCs). Conventional fabrication methods, however, offer limited precision in controlling the pore architecture. To overcome this limitation, this study introduces an integrated approach that combining numerical design with advanced manufacturing to develop anodes with optimized microstructures. A comprehensive numerical model is first established to compute the ideal geometry of straight-through pores for maximizing gas diffusion. Subsequently, the designed architecture is precisely fabricated using a novel semi-solid additive manufacturing (SSAM) technique. Full cells are subsequently assembled via screen-printing and evaluated electrochemically. The cell with an optimized pore spacing of 0.675 mm achieved a peak power density of 1.2 W cm-2 at 800 degrees C, which outperforms conventional slurry-based 3D printed counterparts by 45.6% and establish a new benchmark for intermediate-temperature SOFC performance. This study demonstrates an integrated approach for SOFC anode design that enhances high-power performance through architectural optimization. The SSAM-printed anodes exhibit high mechanical integrity and significantly reduced concentration polarization, providing a promising route for improving the power density of thick-supported cells.

Thermal cycling stability is critical for the practical application of solid oxide electrolysis cells (SOECs) when facing frequent start-up and shutdown operations, accompanied by thermo-mechanical stresses and thus interfacial degradation. To develop deeper insight into the degradation mechanism of SOEC stacks during thermal cycling, a 3-cell SOEC stack was subjected to 5 thermal cycles (400-750 degrees C). The stack exhibited noticeable degradation phenomenon during the initial 3 thermal cycles, whereas the degradation rate decreased in the subsequent thermal cycles. Electrochemical impedance spectroscopy reveals that applying a forward polarization current density of 0.200 A & centerdot;cm-2 after each thermal cycle can partially recover the increased impedance and thus alleviate the degradation caused by thermal cycling. The forward polarization is beneficial for mitigating the migration of Ni toward the electrolyte observed during electrolysis mode. Furthermore, nickel redox cycling can improve the porosity and facilitate gas diffusion of the hydrogen electrode, whereas excessive cycling may promote Ni detachment, thereby reducing the triple-phase boundary length and consequent performance degradation. The oxidation in the central area of the current collector is the direct cause of increased interfacial resistance in the stack.

Nanofibers hold great promise as oxygen electrode materials in solid oxide cells (SOCs). However, conventional fabrication methods-such as slurry processing and high-temperature sintering-inevitably disrupt their delicate nano-architectures. Here, we propose an innovative self-assembly strategy mediated by current polarization to construct La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-delta -Gd 0.1 Ce 0.9 O 2-delta (LSCF-GDC) nanofiber composite film electrodes. This approach largely preserves the fibrous morphology while promoting coherent heterointerfaces, abundant active sites, and efficient electron/ion pathways. Benefiting from this tailored architecture, the electrode achieves a low polarization resistance of 0.117 Omega cm 2 and a peak power density of 1.482 W cm-2 at 800 degrees C. Moreover, in CO 2 electrolysis mode, it delivers an impressive current density of 2.30 A cm-2 at 1.8 V. These results establish nanofiber heterostructure films, enabled by current polarization assembly, as a powerful strategy to simultaneously enhance activity, durability, and mass transport, offering new opportunities for high-performance intermediate-temperature SOCs.

Solid oxide fuel cells (SOFCs), composed of ceramic-based components, are typically assembled in a layered, sandwich-like structure. This configuration is prone to significant thermal stress, which poses challenges to maintaining long-term operational stability. Optimizing temperature and flow distribution uniformity offers a key mitigation strategy. Within the SOFC, the flow path encompasses the manifold, inlet, outlet, ridge, and bank, facilitating gas distribution. This study investigates key geometric parameters of the flow field-namely, manifold size, inlet diameter, and ridge-bank spacing-that significantly affect gas distribution uniformity in solid oxide fuel cells. A hybrid approach combining experimental validation and numerical simulation is employed to explore how these design features influence the internal flow behavior, thermal distribution, and current density patterns. The results offer valuable guidance for structural optimization. It is found that increasing the manifold width to 5 mm enhances the flow uniformity index by over 30 %, indicating its critical role in promoting uniform gas delivery. In contrast, changes in inlet diameter have minimal impact on both flow and temperature profiles. Additionally, introducing inlet flow deflection emerges as an effective strategy for improving uniformity in both thermal and flow distributions.

As an efficient device for energy conversion, solid oxide electrolysis cells (SOECs) can utilize renewable energy to efficiently convert CO 2 into CO, realizing both CO 2 resource utilization and chemical storage of renewable energy.

Solid electrolyte oxygen generation technology has received significant attention as a new generation of oxygen separation technology. However, developing novel oxygen-permeable membrane materials with high permeability at intermediate temperatures remains challenging, particularly for high oxygen ion-conducting electrolytes focused on the 600 degrees C to 700 degrees C range. This paper describes the fabrication and characterization of a ceramic oxygen pump based on Dy-Gd-Er co-doped bismuth oxide (DGESB). The synergistic effect generated by multicomponent doping results in a lower activation energy for ion migration and higher ionic conductivity. By controlling the ratio and total amount of dopant elements, the Dy0.06Gd0.02Er0.02Bi1.9O3 (6D2G2ESB) oxygen ion conductor electrolyte exhibits the highest ionic conductivity (0.31 S/cm at 600 degrees C, 0.43 S/cm at 650 degrees C, and 0.57 S/cm at 700 degrees C). A sandwich-structured oxygen pump was fabricated using Pt electrodes to evaluate the electrolyte's oxygen permeability. At 650 degrees C, the 6D2G2ESB electrolyte-supported membrane (1100 mu m) achieved an oxygen flux of 5.92 mL center dot cm- 2 center dot min- 1 under a 2 V voltage. The electrochemical performance of the oxygen pump across different temperature ranges was investigated, confirming that the 6D2G2ESB electrolyte stabilized by ternary rare-earth doping exhibits outstanding oxygen permeability stability between 600 degrees C and 700 degrees C. The 6D2G2ESB-based oxygen pump is a promising rapid electrochemical oxygen separation system suitable for intermediate-temperature operating environments.

ABO3 perovskite-type proton-conductors have become pivotal materials for next-generation protonic SOCs. The distinctive proton-transport mechanisms exhibited by these materials, coupled with their notable chemical stability and structural compatibility with a wide range of electrodes, facilitate efficient proton conduction across the temperature range of 300–700 °C. Advancements in the field of ABO3 perovskite-type proton-conductors such as Ba-, Sr-, and La-based electrolytes and their solid solutions have been driven by significant progress in composition design, defect chemistry control, and microstructural engineering. This review summarizes recent developments, major challenges, and future directions for current ABO3 perovskite-type proton-conductors in SOC technologies. We compile representative proton-conductivity data under humid conditions, compare proton-transport behavior and chemical robustness among different perovskite families, and discuss strategies to improve proton mobility and stability in CO2-rich, humid, or reducing atmospheres. It is evident that a concerted effort in the field of proton-conducting perovskite research, encompassing composition optimization, defect regulation, stability enhancement, and device-level engineering, is yielding substantial advancements. These advancements are establishing a robust foundation for the development of durable, high-performance proton-conducting perovskites. Furthermore, these advancements are expediting the progression of perovskite-based proton conductors towards their practical application in the domain of protonic ceramic energy conversion.

Perovskite-type oxides hold promise as supports for Ir-based acidic oxygen evolution reaction (OER) catalysts, yet their instability under harsh conditions limits practical application. Defect engineering of IrOx-perovskite heterostructures offers new opportunities for acidic oxygen evolution catalysis. Here, we demonstrate thermal-reconstructed oxygen defect regulation in IrOx@La1.2Sr0.8Ni0.6Fe0.4O4+δ (IrOx@LSNF) catalysts, where controlled calcination induces in situ growth of oxygen-deficient amorphous IrOx on Ruddlesden-Popper perovskite. Thermal reconstruction at 250°C generates oxygen-defect-rich amorphous IrOx on LSNF (IrOx@LSNF-250), creating strong metal-metal oxides support interaction (MMSI) that enhances active-site utilization while favoring the lattice oxygen participation mechanism (LOM) for superior OER activity. Remarkably, the perovskite-anchored IrOx heterostructure maintains considerable durability in half-cell acidic media against LOM-induced collapse, demonstrating how defect-engineered thermal reconstruction simultaneously addresses activity-stability trade-offs in acidic OER catalysis. The optimized OER performance of IrOx@LSNF-250 in acidic media are attributed to perovskite-anchored Ir species suppressing dissolution, together with thermal-reconstruction-enriched oxygen defects optimizing LOM. This work establishes a paradigm for defect-engineered heterostructures via thermal reconstruction, advancing perovskite-based OER catalysts beyond conventional stability-activity trade-offs in acidic media.

The development of oxygen electrodes for reversible solid oxide cells (RSOCs) is hindered by insufficient catalytic activity, limited stability, and a mismatch in the thermal expansion coefficients (TEC) with electrolytes. Herein, we design and synthesize a novel perovskite oxide, La0.6Ca0.4Fe0.8Ni0.1Co0.1O3-δ (LCFNC), using a multi-element B-site synergistic doping strategy. Systematic investigations reveal that the incorporation of Fe stabilizes the perovskite lattice, while the addition of Ni and Ca effectively suppresses the TEC (to 12.7 × 10-6 K-1 after GDC compositing), ensuring excellent electrolyte compatibility. Furthermore, the cooperative interplay between Ni, Co, and Fe establishes ternary active centers, significantly increasing the concentration of surface oxygen vacancies. Full-cell measurements demonstrate a peak power density of 1.60 W·cm-2 at 800°C and a high electrolysis current density of 1.82 A·cm-2 at 1.3 V. Stability tests, including 100 h of constant-current electrolysis at 750°C and 24 reversible operation cycles, highlight exceptional interfacial and structural stability. More importantly, the assembled industrial-sized RSOCs (15 × 15 cm2) achieve an output power of 64 W in fuel cell mode and a maximum current of 105 A in electrolyzer mode at 800°C, demonstrating its potential for practical applications. This work elucidates the mechanistic role of multi-element B-site regulation and provides an effective design principle for oxygen electrode materials that enhance activity, stability, and compatibility simultaneously, thus advancing the practical deployment of high-performance RSOCs.

Protonic ceramic fuel cells (PCFCs) offer promising solutions for efficient and flexible energy conversion at intermediate temperatures (300-700 degrees C), addressing critical challenges of material degradation and high operational costs in solid oxide fuel cells. However, the development of cathode materials with enhanced proton conductivity, oxygen reduction reaction (ORR) activity, and long-term stability remains an imminent challenge. PrBaB2O5 (B = transition metal) double perovskites oxides (DPOs) materials have emerged as high-potential alternatives due to the superior catalytic activity, high oxygen vacancy concentration, and good electronic conductivity at intermediate temperatures. Here, the PrBa0.8Ca0.2Fe2-xCoxO5+delta DPOs structure was designed with ordered arrangement of Pr and Ba cations. By adjusting the Fe/Co ratio in B-site, a transition from a simple cubic structure to a double perovskite structure was successfully achieved. The synthesized PrBa0.8Ca0.2Fe0.4Co1.6O5+delta (PBCX-16) with a double-perovskite structure demonstrates exceptional performance, including a peak power density of 1.511 W cm-2 at 700 degrees C and a remarkably low polarization impedance of 0.068 Omega cm2. Furthermore, the cell with PBCX-16 cathode can stably operate for up to 250 h at 600 degrees C. This work offers the innovative insights into the structural modulation of cathode materials and advances the development of cathodes for PCFCs.