Tailoring OER/ORR activity in TM1N4 catalysts through first-/second-shell nitrogen doping: a density functional theory investigation

Proposing an effective modification strategy to optimize catalyst reaction potentials is crucial for enhancing catalytic performance. In this study, we employed a combined approach by adjusting nitrogen dopants in the first- and second-shell environments to tailor the OER/ORR reaction potentials of Fe₁N₄, Co₁N₄, and Ni₁N₄ active centers. Using density functional theory simulations, we systematically compared the effects of first- and second-shell nitrogen dopants on the local atomic/electronic structures and catalytic activities. The results showed that first-shell nitrogen dopants had a dominant influence on the reaction potentials, while second-shell dopants provided fine-tuning adjustments. This combined regulation of nitrogen dopants in both shells significantly lowered the overpotentials for the OER and ORR, enhancing the overall catalytic performance. Specifically, N3-doped Fe₁-pyrrole N₄ and N2-doped Fe₁-pyridine N₄ active centers demonstrated the lowest overpotentials of 209 mV for the OER and 196 mV for the ORR, respectively. This strategy offers a promising pathway for designing more efficient catalysts.