Direct methane protonic ceramic fuel cells with self-assembled Ni-Rh bimetallic catalyst.

Hong, Kyungpyo; Choi, Mingi; Bae, Yonggyun; Min, Jihong; Lee, Jaeyeob; Kim, Donguk; Bang, Sehee; Lee, Han-Koo et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

Direct methane protonic ceramic fuel cells are promising electrochemical devices that address the technical and economic challenges of conventional ceramic fuel cells. However, Ni, a catalyst of protonic ceramic fuel cells exhibits sluggish reaction kinetics for CH<sub>4</sub> conversion and a low tolerance against carbon-coking, limiting its wider applications. Herein, we introduce a self-assembled Ni-Rh bimetallic catalyst that exhibits a significantly high CH<sub>4</sub> conversion and carbon-coking tolerance. It enables direct methane protonic ceramic fuel cells to operate with a high maximum power density of ~0.50 W·cm<sup>-2</sup> at 500 °C, surpassing all other previously reported values from direct methane protonic ceramic fuel cells and even solid oxide fuel cells. Moreover, it allows stable operation with a degradation rate of 0.02%·h<sup>-1</sup> at 500 °C over 500 h, which is ~20-fold lower than that of conventional protonic ceramic fuel cells (0.4%·h<sup>-1</sup>). High-resolution in-situ surface characterization techniques reveal that high-water interaction on the Ni-Rh surface facilitates the carbon cleaning process, enabling sustainable long-term operation.