Direct ethanol solid oxide fuel cells integrated with internal reforming for renewable power generation

A High-Performance and Durable Direct-Ammonia Symmetrical Solid Oxide Fuel Cell with Nano La0.6Sr0.4Fe0.7Ni0.2Mo0.1O3-δ-Decorated Doped Ceria Electrode

Solid oxide fuel cells (SOFCs) offer a significant advantage over other fuel cells in terms of flexibility in the choice of fuel. Ammonia stands out as an excellent fuel choice for SOFCs due to its easy transportation and storage, carbon-free nature and mature synthesis technology. For direct-ammonia SOFCs (DA-SOFCs), the development of anode catalysts that have efficient catalytic activity for both NH3 decomposition and H2 oxidation reactions is of great significance. Herein, we develop a Mo-doped La0.6Sr0.4Fe0.8Ni0.2O3-δ (La0.6Sr0.4Fe0.7Ni0.2Mo0.1O3-δ, LSFNM) material, and explore its potential as a symmetrical electrode for DA-SOFCs. After reduction, the main cubic perovskite phase of LSFNM remained unchanged, but some FeNi3 alloy nanoparticles and a small amount of SrLaFeO4 oxide phase were generated. Such reduced LSFNM exhibits excellent catalytic activity for ammonia decomposition due to the presence of FeNi3 alloy nanoparticles, ensuring that it can be used as an anode for DA-SOFCs. In addition, LSFNM shows high oxygen reduction reactivity, indicating that it can also be a cathode for DA-SOFCs. Consequently, a direct-ammonia symmetrical SOFC (DA-SSOFC) with the LSFNM-infiltrated doped ceria (LSFNM-SDCi) electrode delivers a superior peak power density (PPD) of 487 mW cm-2 at 800 °C when NH3 fuel is utilised. More importantly, because Mo doping greatly enhances the reduction stability of the material, the DA-SSOFC with the LSFN-MSDCi electrode exhibits strong operational stability without significant degradation for over 400 h at 700 °C.

Self-hydrating of a ceria-based catalyst enables efficient operation of solid oxide fuel cells on liquid fuels

The commercialization of solid oxide fuel cells (SOFCs) that run on liquid hydrocarbon fuels is hindered by the poor coking tolerance of the state-of-the-art anode. Among the strategies developed, modulating the reforming reaction site's local steam/carbon ratios to enhance the coking tolerance is efficient but challenging. Here we report our rational design of a ceria-based catalyst (with a nominal composition of Ce0.95Ru0.05O2-δ, CR5O) that demonstrates remarkable tolerance to coking while maintaining excellent activity for direct utilization of liquid fuels in SOFCs. Under operating conditions, the catalyst is transformed to a partially reduced oxide frame covered with Ru nanoparticles (Ru/Ce0.95Ru0.05-xO2-δ, Ru/CR5-xO), as confirmed by experimental analyses. The Ru/CR5-xO demonstrates excellent self-hydration capability to remove the coke. When applied to the Ni-yttria-stabilized zirconia (Ni-YSZ) anode of an SOFC with liquid fuels, the catalyst enables excellent performance, achieving a peak power density of 1.010 W cm-2 without coking for ∼200 h operation (on methanol) at 750 °C. Furthermore, density functional theory calculations reveal that the high activity and coking tolerance of the Ru/CR5-xO catalyst-coated Ni-YSZ anode is attributed to the reduced energy barrier for the rate-limiting step and the formation of a COH intermediate for rapid carbon removal.

A mini review of the recent progress of electrode materials for low-temperature solid oxide fuel cells

Lowering the operating temperature (450-650 °C) of solid oxide fuel cells (SOFCs) faces the intrinsic challenge of sluggish electrode reaction kinetics in the low temperature (LT) range. To accelerate the electrode reaction rate, many efforts have been put into the optimization of electrode composition and morphology. In this review, we have summarized recent developments of LT-SOFC electrodes, including anode and cathode materials. For anode performance improvement, the internal structure design, fine anode structure, reforming layer addition, and in situ exsolution techniques are introduced and their related functionalities are also explained, respectively. While for the cathode, we focus on the perovskite-type materials because of their superior catalytic performance and relatively good stability. The optimization of perovskite composition, including A site alkali or alkali-earth metal doping and B site variable-valence transition metal doping, is discussed in detail based on their effects on oxygen reduction reaction (ORR). Besides, nanostructure assembly and 3D morphology design are also recent hotspots for cathode research. Finally, we also propose several research directions in this field, hoping to provide guidelines for future research.