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<p>In this DFT study, we systematically investigated PN-co-doped graphene-supported dual-atom catalysts (DACs) comprising homonuclear and heteronuclear pairs of Fe, Co, and Ni for enhancing the kinetics of the four-electron oxygen reduction reaction (ORR). Binding and formation energy analyses confirm the thermodynamic stability of all M1M2@NPxC configurations, indicating strong resistance to metal atom diffusion and aggregation. The adsorption geometries and energies of key ORR intermediates (*O<sub>2</sub>, *OOH, *O, and *OH) were examined alongside free energy changes for the four elementary steps, revealing that P-doping in M1M2@NC systems enhances O<sub>2</sub> activation and optimizes intermediate reduction. Electron transfer was found to play a crucial role in chemisorption and activation, with O<sub>2</sub> predominantly binding in a side-on configuration to the metal dimers. Theoretical overpotentials (η<sub>ORR</sub>), calculated via the Limiting potential method, ranged from 0.345 to 1.217&#xa0;V. Ni-based DACs, particularly NiNi@NP<sub>5</sub>C (<i>η</i> = 0.345&#xa0;V), exhibit the most favorable free energy profiles and the highest predicted catalytic activity. Heterodimeric systems such as FeCo@NP<sub>x</sub>C, FeNi@NP<sub>x</sub>C, and CoNi@NP<sub>x</sub>C also demonstrate promising performance. Strong linear correlations are observed between Δ<i>G</i>*<sub>OOH</sub> and Δ<i>G</i>*<sub>OH</sub> (<i>R</i><sup>2</sup> = 0.86), consistent with their similar binding modes via a single oxygen atom, whereas correlations with Δ<i>G</i>*<sub>O</sub> are weaker. These findings highlight the synergistic benefits of P-doping and dual-metal active sites in designing efficient, platinum-free ORR electrocatalysts for fuel cell applications.</p>

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Dual-atom catalysts based on PN-co-doped graphene: a comparative study of iron, cobalt, and nickel for ORR

  • 期刊论文

  • 发表日期：

    2025年9月17日

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  • Pegah Ghafouri Mirsaraei,
  • Maryam Anafcheh,
  • Elaheh Ahmadi

摘要

In this DFT study, we systematically investigated PN-co-doped graphene-supported dual-atom catalysts (DACs) comprising homonuclear and heteronuclear pairs of Fe, Co, and Ni for enhancing the kinetics of the four-electron oxygen reduction reaction (ORR). Binding and formation energy analyses confirm the thermodynamic stability of all M1M2@NPxC configurations, indicating strong resistance to metal atom diffusion and aggregation. The adsorption geometries and energies of key ORR intermediates (*O2, *OOH, *O, and *OH) were examined alongside free energy changes for the four elementary steps, revealing that P-doping in M1M2@NC systems enhances O2 activation and optimizes intermediate reduction. Electron transfer was found to play a crucial role in chemisorption and activation, with O2 predominantly binding in a side-on configuration to the metal dimers. Theoretical overpotentials (ηORR), calculated via the Limiting potential method, ranged from 0.345 to 1.217 V. Ni-based DACs, particularly NiNi@NP5C (η = 0.345 V), exhibit the most favorable free energy profiles and the highest predicted catalytic activity. Heterodimeric systems such as FeCo@NPxC, FeNi@NPxC, and CoNi@NPxC also demonstrate promising performance. Strong linear correlations are observed between ΔG*OOH and ΔG*OH (R2 = 0.86), consistent with their similar binding modes via a single oxygen atom, whereas correlations with ΔG*O are weaker. These findings highlight the synergistic benefits of P-doping and dual-metal active sites in designing efficient, platinum-free ORR electrocatalysts for fuel cell applications.