Transition-metal-decorated germanene as promising catalyst for removing CO contamination in H2

• Fe and Ru adatoms on germanene were proposed as catalysts for removing the CO contamination in H2.
• Under the catalysis of Fe and Ru adatoms, CO in H2 could be transformed into HCHO.
• Germanene substrate could prevent the aggregation of Fe and Ru adatoms.

Single-layer germanene was proposed as substrate for single-atom transition metal catalysts with much larger adsorption energies and higher thermal migration barriers than graphene. By density functional theory calculations, the electronic properties, thermal stabilities and catalytic abilities of Au, Fe, Ni, Pd, Pt and Ru adatoms on single-layer germanene were theoretically investigated. The results indicate that the CO contamination in H2 could be transformed into HCHO under the catalysis of Fe and Ru adatoms. For Fe and Ru adatoms, the three-step catalytic reactions were found both thermodynamically and kinetically favorable, with stable reaction intermediates and low potential barriers. Furthermore, Fe and Ru adatoms could be stably adsorbed on germanene with large adsorption energies and high thermal migration barriers, preventing the aggregation of Fe and Ru on germanene. However, for Au, Ni, Pd and Pt adatoms, the reaction intermediates are thermodynamically unfavorable so that the catalytic reactions should be difficult to proceed. By contrast, Fe and Ru adatoms on single-layer germanene should be excellent catalysts for removing the CO contamination from H2 feed gas of fuel cells.

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