Self-assembled Ni-Rh bimetallic catalyst for the exceptional performance and stability of direct methane protonic ceramic fuel cells

Abstract Direct methane PCFCs are promising electrochemical devices that address the technical and economic challenges associated with using pure hydrogen, such as the high cost of green production, transportation, and long-term storage. However, Ni, a conventional monometallic catalyst has sluggish reaction kinetics and a low tolerance for carbon cocking under CH4 operation, limiting its wider applications. Herein, we develop a self-assembled Ni-Rh bimetallic catalyst through Ni exsolution and Rh surface decoration in a fuel electrode. The Ni-Rh bimetallic catalyst shows remarkably high catalytic activity with an exceptional performance of ~ 0.50 W/cm2 at 500 ℃. Moreover, the catalyst significantly improves the stability with a degradation rate of 0.02%/h at 500 ℃; this value is ~ 20-fold lower than that of conventional PCFC (0.4%/h). Synchrotron-based in situ X-ray photoelectron spectroscopy reveals that the Ni-Rh bimetallic catalyst initiates a self-carbon cleaning process due to its high-water dissociation reaction, allowing sustainable operation.