A single-atom potential confinement strategy for stabilizing rhodium nanocatalysts in methane oxidation

Operating nanometal catalysts under harsh reaction conditions often leads to their disintegration into less active single atoms or clusters, which is considered as a primary cause of catalyst deactivation and loss of active components. In the current work, our theoretical calculations on CeO₂-supported Rh catalysts first reveal that pre-filling surface vacancies with suitable single metal atoms renders the subsequent anchoring of Rh atoms on supports energetically unfavorable. Guided by this insight, we propose a simple strategy that pre-anchored guest atoms to generate a high-potential confinement field, which thermodynamically suppresses the release of atoms from nanoparticles and their subsequent deposition onto the support, thereby stabilizing Rh nanocatalysts across a wide temperature range during methane oxidation while maintaining high activity. Catalytic tests of simulated engine methane emissions, coupled with environmental scanning transmission electron microscopy characterizations, reveal that both supported Rh nanoparticles with and without pre-anchored single atoms demonstrate initial methane oxidation activity at temperatures below 200 °C, while only single-atom-confined nanoparticles retain structural integrity and full activity after 800 °C aging, whereas unprotected ones degrade into single atoms and lose low-temperature reactivity, thereby confirming the effectiveness of our confinement strategy. Further theoretical calculations unveil that the low-temperature activity is driven by Rh nanoparticles with pronounced electron delocalization, rather than Rh single-atom interacting with the CeO₂ support. This work offers a new design strategy based on a novel energy confinement effect for dynamically stabilizing supported metal nanoparticle catalysts even under severe conditions while maintaining exceptional catalytic activity, opening up new avenues for catalyst design through alternative approaches beyond conventional metal-support interactions to regulate and enhance nanoparticle behavior and reactivity.