Slightly ruthenium doping enables better alloy nanoparticle exsolution of perovskite anode for high-performance direct-ammonia solid oxide fuel cells

Abstract

• Slightly Ru doping promotes the exsolution of alloy nanoparticles in perovskite anode. • Ru doping greatly reduces the particle size and increase the amount of exsolved alloy nanoparticles. • Ru doped perovskite anode shows superior catalytic activity for NH 3 decomposition and anti-sintering capability. • DA-SOFCs with Ru doped perovskite anode exhibits a superior operational stability to Ru-free counterpart. Fuel flexibility is one of the most distinguished advantages of solid oxide fuel cells (SOFCs) over other low-temperature fuel cells. Furthermore, the combination of ammonia fuel and SOFCs technology should be a promising clean energy system after considering the high energy density, easy transportation/storage, matured synthesis technology and carbon-free nature of NH 3 as well as high efficiency of SOFCs. However, the large-scale applications of direct-ammonia SOFCs (DA-SOFCs) are strongly limited by the inferior anti-sintering capability and catalytic activity for ammonia decomposition reaction of conventional nickel-based cermet anode. Herein, a slightly ruthenium (Ru) doping in perovskite oxides is proposed to promote the alloy nanoparticle exsolution, enabling better DA-SOFCs with enhanced power outputs and operational stability. After treating Ru-doped Pr 0.6 Sr 0.4 Co 0.2 Fe 0.75 Ru 0.05 O 3-δ single-phase perovskite in a reducing atmosphere, in addition to the formation of two layered Ruddlesden-Popper perovskites and Pr 2 O 3 nanoparticles (the same as the Ru-free counterpart, Pr 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ), the exsolution of CoFeRu-based alloy nanoparticles is remarkably promoted. Such reduced Pr 0.6 Sr 0.4 Co 0.2 Fe 0.75 Ru 0.05 O 3-δ composite anode shows superior catalytic activity and stability for NH 3 decomposition reaction as well as anti-sintering capability in DA-SOFCs to those of reduced Pr 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ due to the facilitated nanoparticle exsolution and stronger nanoparticle/substrate interaction. This work provides a facile and effective strategy to design highly active and durable anodes for DA-SOFCs, promoting large-scale applications of this technology.