Researchers at MIT have developed a highly active bifunctional electrocatalyst composed of platinum-gold nanoparticles (PtAu) for rechargeable lithium-air batteries. This catalyst, PtAu/C, significantly improves the round-trip efficiency of these batteries, which is the ratio of discharge to charge voltage. The study shows that PtAu/C achieves a round-trip efficiency of 73%, the highest reported for lithium-air batteries. The PtAu nanoparticles, synthesized and supported on carbon, exhibit enhanced oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics. The catalyst's surface composition, with a Pt/Au ratio of approximately 60/40%, is crucial for its catalytic activity. The PtAu/C catalyst outperforms pure carbon, Pt/C, and Au/C in terms of charging voltage and round-trip efficiency. The study also demonstrates that the PtAu/C catalyst can deliver high discharge and charge capacities at various current densities, with a round-trip efficiency of up to 77% at 50 mA/g. The results suggest that PtAu nanoparticles are effective in catalyzing both ORR and OER in lithium-air batteries, with surface Pt and Au atoms playing key roles in these reactions. This research highlights the potential of PtAu nanoparticles as a promising strategy for developing highly active bifunctional catalysts for lithium-air batteries.Researchers at MIT have developed a highly active bifunctional electrocatalyst composed of platinum-gold nanoparticles (PtAu) for rechargeable lithium-air batteries. This catalyst, PtAu/C, significantly improves the round-trip efficiency of these batteries, which is the ratio of discharge to charge voltage. The study shows that PtAu/C achieves a round-trip efficiency of 73%, the highest reported for lithium-air batteries. The PtAu nanoparticles, synthesized and supported on carbon, exhibit enhanced oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics. The catalyst's surface composition, with a Pt/Au ratio of approximately 60/40%, is crucial for its catalytic activity. The PtAu/C catalyst outperforms pure carbon, Pt/C, and Au/C in terms of charging voltage and round-trip efficiency. The study also demonstrates that the PtAu/C catalyst can deliver high discharge and charge capacities at various current densities, with a round-trip efficiency of up to 77% at 50 mA/g. The results suggest that PtAu nanoparticles are effective in catalyzing both ORR and OER in lithium-air batteries, with surface Pt and Au atoms playing key roles in these reactions. This research highlights the potential of PtAu nanoparticles as a promising strategy for developing highly active bifunctional catalysts for lithium-air batteries.