Direct Methylcyclohexane Protonic Ceramic Fuel Cells with Anode Catalyst Modifications

Abstract A direct methylcyclohexane (MCH)-fueled protonic ceramic fuel cell was demonstrated for the first time using an anode-supported protonic ceramic fuel cell (PCFC) operating at 400 °C without external hydrogen feeding, achieving a peak power density of approximately 3–4 mW/cm2. A Ni–BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) anode was used as the baseline MCH-dehydrogenation catalyst and was further modified by Pt infiltration, Pt surface layering, and the deposition of a Ni–Zn–BZCYYb (NBZ) overlayer. Among the tested strategies, the Pt-layered anode showed the highest activity, delivering up to 96% toluene (TOL) selectivity at 1.2% MCH/Ar, while the NBZ overlayer also improved TOL formation relative to the unmodified anode. Product analysis confirmed highly selective MCH-to-TOL dehydrogenation with minimal side reactions, and TOL formation was independent of the electrode potential, indicating a purely catalytic process. By contrast, the power-generation current was limited by the amount of produced H2, confirming that the electricity originated from the electrochemical oxidation of the in situ generated H2. Although the current remained low, these results provide clear proof-of-concept that PCFCs can directly utilize MCH and that the Pt-layering and Ni–Zn modifications effectively enhance the low-temperature dehydrogenation performance of future liquid organic hydrogen carrier (LOHC)-compatible PCFC systems.