Intermediate-temperature direct ammonia solid oxide fuel cell engineered by surface modification with cobalt and gadolinium-doped ceria

Abstract

Intermediate-temperature direct ammonia solid oxide fuel cells (SOFCs) hold great promise for advancing fuel cell commercialization and supporting a hydrogen-based society, owing to ammonia's well-established supply chain and high energy density. However, their widespread adoption is hindered by limited performance and degradation issues, primarily stemming from sluggish ammonia decomposition kinetics and electrode poisoning. In this study, we present a surface-modified anode featuring both inverse and conventional Co–Gd-doped ceria (GDC) nanocatalysts distributed across the entire Ni/yttria-stabilized zirconia backbone, delivering enhanced catalytic activity and stability. This enables operating at maximum power density of 0.225 W cm−2 at 600 °C, among the highest reported for intermediate-temperature direct ammonia SOFCs to date. Furthermore, the cell exhibits long-term operational stability, with a degradation rate of just 3.3% over 500 h at 600 °C, approximately 2.4 times lower than that of a conventional commercial cell (9.1%). Density functional theory calculations and surface spectroscopy analyses reveal that (1) Cobalt incorporation into the Ni backbone enhances NHx (x = 1–3) scission due to increased basicity; (2) GDC introduction induces oxide–metal strong interactions (OMSIs), which not only promote NHx scission via lattice oxygen but also accelerate the 2N recombination reaction through enhanced charge transfer from corner-site Ce.