The unique characteristics of nanofibers in rational electrode design enable effective utilization and maximizing material properties for achieving highly efficient and sustainable CO₂ reduction reactions (CO₂RRs) in solid oxide electrolysis cells (SOECs). However, practical application of nanofiber-based electrodes faces challenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte. To tackle this challenge, a novel hybrid nanofiber electrode, La_0.6Sr_0.4Co_0.15Fe_0.8Pd_0.05O_3-δ (H-LSCFP), is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique. After consecutive treatment in 100% H₂ and CO₂ at 700 °C, LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface, enhancing CO₂ adsorption. The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^-2 in CO₂ at 800 °C and 1.5 V, setting a new benchmark among reported nanofiber-based electrodes. Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO₂RR. The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure, paving the way for further advancements and nanofiber applications in CO₂-SOECs.

An universal oxygen-electrode, compatible to both oxygen- and proton-conducting solid oxide electrochemical cells (O-SOCs and H-SOCs, respectively), as well as for electricity and hydrogen production purpose is showcased.

A multiscale architectured solid oxide fuel cell is demonstrated by applying a large-area ceramic micropatterning and thin-film deposition processes.

The 2012 Department of Energy (DOE) budget request significantly reduces fuel cell RD&D funding and would cease to support the Solid State Energy Conversion Alliance (SECA), DOE's solid oxide fuel cell (SOFC) program. This would be a grave mistake considering the US's historic dominance in fuel cell RD&D, exciting recent technological advancements in fuel cells, and clear positive market signals around the globe. In this paper we discuss DOE's energy RD&D policy, how SOFCs address every key DOE strategy, and why recent advances should make SOFCs an integral part of our energy RD&D policy. Moreover, we compare the prospects of low temperature SOFCs with the more common proton exchange membrane fuel cell (PEMFC) in the absence of a hydrogen infrastructure.

The unique characteristics of nanofibers in rational electrode design enable effective utilization and maximizing material properties for achieving highly efficient and sustainable CO₂ reduction reactions (CO₂RRs) in solid oxide electrolysis cells (SOECs). However, practical application of nanofiber-based electrodes faces challenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte. To tackle this challenge, a novel hybrid nanofiber electrode, La_0.6Sr_0.4Co_0.15Fe_0.8Pd_0.05O_3-δ (H-LSCFP), is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique. After consecutive treatment in 100% H₂ and CO₂ at 700 °C, LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface, enhancing CO₂ adsorption. The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^-2 in CO₂ at 800 °C and 1.5 V, setting a new benchmark among reported nanofiber-based electrodes. Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO₂RR. The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure, paving the way for further advancements and nanofiber applications in CO₂-SOECs.

An universal oxygen-electrode, compatible to both oxygen- and proton-conducting solid oxide electrochemical cells (O-SOCs and H-SOCs, respectively), as well as for electricity and hydrogen production purpose is showcased.

A multiscale architectured solid oxide fuel cell is demonstrated by applying a large-area ceramic micropatterning and thin-film deposition processes.

The 2012 Department of Energy (DOE) budget request significantly reduces fuel cell RD&D funding and would cease to support the Solid State Energy Conversion Alliance (SECA), DOE's solid oxide fuel cell (SOFC) program. This would be a grave mistake considering the US's historic dominance in fuel cell RD&D, exciting recent technological advancements in fuel cells, and clear positive market signals around the globe. In this paper we discuss DOE's energy RD&D policy, how SOFCs address every key DOE strategy, and why recent advances should make SOFCs an integral part of our energy RD&D policy. Moreover, we compare the prospects of low temperature SOFCs with the more common proton exchange membrane fuel cell (PEMFC) in the absence of a hydrogen infrastructure.

Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy.

Solid oxide electrochemical cells (SOCs) are promising next-generation, eco-friendly, and efficient energy conversion devices. However, their high operating temperatures hinder commercialization, primarily due to the lack of highly durable and active materials for low-temperature operation. Herein, a highly stable and conductive δ-Bi₂O₃-based ionic conductor is introduced, in which unoccupied oxygen sites are mediated by F^- ions to enhance structural stability and conductivity. The optimized material exhibits an exceptional ionic conductivity of 0.228 S cm^-1 at 600 °C, representing a more than 70-fold increase compared to conventional Y-doped zirconia, while maintaining excellent long-term stability. Density functional theory calculations reveal that F^- incorporation stabilizes the disordered anion sublattice, reinforcing the cation-anion bonding strength and enhancing the structural symmetry of the δ-cubic fluorite structure. When integrated into a composite oxygen electrode, the developed ionic conductor enables superior electrochemical performances in SOCs, achieving 0.98 W cm^-2 in fuel cell mode and 0.63 A cm^-2 at 1.3 V in electrolysis mode at 600 °C. These findings provide insights into the rational design of stable and active materials for high-performance SOCs, facilitating efficient operation at reduced temperatures and advancing their practical viability.

Abstract Protonic ceramic electrochemical cells (PCECs) offer a promising platform for efficient energy conversion and storage at reduced temperatures (<650 °C). However, the commercial viability of PCECs remains hindered by the limited durability and sluggish oxygen electrocatalysis at the air electrode. Herein, a high‐entropy perovskite oxide (HEPO), Pr 0.2 Ba 0.2 Sr 0.2 La 0.2 Nd 0.2 CoO 3‐δ (PBSLNC), in a nanofiber architecture is presented as a bifunctional air electrode material for reversible PCEC operation. The unique A‐site compositional complexity promotes defect tolerance, abundant oxygen vacancies, rapid surface exchange kinetics while maintaining exceptional phase stability in harsh environments. Density functional theory calculations elucidate the entropically modulated Co environment that enhances hydroperoxide adsorption—a key step for oxygen electrocatalysis, thereby facilitating both oxygen reduction and evolution reactions. When deployed into a PCEC configuration, the PBSNLC nanofiber electrode achieves a peak power density of 1.4 W cm −2 at 650 °C and electrolysis current density of 3.98 A cm −2 at 650 °C, along with outstanding operational stability during continuous operation for over 1000 h. These findings provide valuable guidance for the strategic design of highly efficient and stable bifunctional air electrodes for PCECs.

It is indicated that water can be an active motif for nanoparticle ex-solution. Yet, only a handful of studies are available, if possible, limited to the elemental composition of Ba(Co,Fe,Zr,Y)O3−δ as a mother oxide. Here we prove the versatility of water-mediated ex-solution by expanding the perovskite palettes. Among these, our selected composition (i.e., Ag ex-solved Ba0.95Ag0.05Co0.8Nb0.1Ta0.1O3-δ, e-BACNT) is demonstrated as an oxygen electrode material for protonic ceramic electrochemical cells, promoting efficient reversible fuel-power generation. Thereby, a peak power density of ∼1.81 W cm–2 and water-splitting current density of ∼2.93 A cm–2 at 1.3 V and 650 °C are achieved within a single cell. Apart from its notable cell performances, this work unveils new opportunities for creating functional metal-oxide heterointerfaces.