A degradation-free platform for intrinsic comparison of metal nanoparticles in methane-fueled SOFC anodes

Abstract

Solid oxide fuel cells (SOFCs) offer a compelling route for direct utilization of various fuels such as CH₄. Although perovskite-based ceramic anodes mitigate carbon coking issues encountered in conventional Ni-YSZ electrodes, their sluggish electrochemical kinetics necessitate the incorporation of metal nanocatalysts. However, nanoparticle sintering, carbon-induced degradation, and uncontrolled dispersion obscure intrinsic catalytic effects, making rational catalyst selection largely empirical. Here, we present a degradation-free evaluation platform based on a porous Pr_0.5Ba_0.5MnO_3−δ (PBMO) anode, integrating colloidal synthesis of monodisperse Pt, Ru, and Ni nanoparticles with an ultrathin Al₂O₃ overlayer deposited by atomic layer deposition (ALD). The PBMO scaffold provides a hydrocarbon-compatible perovskite framework, while uniform particle size and spatial distribution enable fair comparison across catalyst types. The conformal Al₂O₃ coating stabilizes the nanoparticles without altering their catalytic nature. Under wet CH₄ at 700 °C, Pt delivered the most pronounced enhancement, achieving a 3-fold reduction in area-specific resistance without performance degradation, followed by Ru and Ni. This result provides direct evidence of intrinsic catalytic behavior that becomes apparent only under stabilized conditions. Collectively, these findings establish a robust methodology for intrinsic, size- and degradation-independent assessment of nanocatalysts, and further provides a framework that can guide the rational design of high-performance SOFC electrodes.