High-throughput screening of dual atom catalysts for oxygen reduction and evolution reactions and rechargeable zinc-air battery

We provide the rational design of dual atom catalysts (DACs) supported on nitrogen-doped graphene for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through high-throughput computational screening of M₁M₂N6-DAC systems, where M₁ and M₂ represent Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, or Pt metals. We predict that FeRuN6-DAC at the summit of the volcano plot exhibits a low theoretical ORR overpotential (η^ORR) of 0.24 V and a low theoretical OER overpotential (η^OER) of 0.19 V. The low η^ORR and η^OER result from the catalytic performance of the Fe site being tuned to electronic properties that facilitate adsorption and desorption of the OH* intermediate. Inspired by these hybrid density functional theory (DFT) computational and machine learning (ML) results, we synthesized FeRuN6-DAC, FeN4-SAC, and RuN4-SAC and characterized them using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and in-situ electron spin resonance (ESR). Our in-situ ESR spectroscopy signifies that the spin of the Fe active site increases with increasing applied potential due to the increase in the concentration of OH* intermediate on Fe. We verified experimentally the predicted catalytic performances, finding that FeRuN6-DAC leads to an experimental ORR overpotential of 0.29 V with a Tafel slope of 104 mVdec⁻¹ and an OER overpotential of 0.27 V with a Tafel slope of 124 mVdec⁻¹. The rechargeable Zinc-air battery setup was fabricated with FeRuN6-DAC in place of the cathode, showing a maximum power density of 0.45 W/cm² at the current density of 0.44 A/cm² and good stability after 120 cycles. According to our findings, we demonstrate that DFT-guided strategies are useful for designing advanced DACs applicable to ORR, OER, and Zinc-air battery applications.