Multi-Site Electrocatalysts Boost pH-Universal Nitrogen Reduction by High-Entropy Alloys

Electrocatalytic nitrogen reduction reaction (NRR) has been an important area for many scientists. However, high voltage requirements, low NH₃ yield, and poor stability remain the biggest challenges for NRR. Here, novel high-entropy alloys RuFeCoNiCu nanoparticles with small size (≈16 nm) and uniformity, prepared in oil phase at atmospheric pressure and low temperature (≤250 °C) are reported for the first time and are applied to NRR. According to the experiments, there is a high NH₃ yield at a low overpotential. It has a surprising NH₃ yield of 57.1 µg h^–1 mg^–1_cat(11.4 µg h^–1 cm^–2) at 0.05 V versus RHE in 0.1 m KOH, and the corresponding Faradaic efficiency reaches 38.5%, which is the electrocatalyst with the highest NH₃ yield at the voltage of 0.05 V versus RHE reported so far. Similarly, the material also exhibits excellent electrochemical properties in other electrolytes such as 0.1 m Li₂SO₄, 0.1 m Na₂SO₄, and 0.1 m HCl electrolytes. Besides, after the 100 h test, only slightly diminished in activity. Theoretical calculation shows that Fe surrounded by alloy metals is the best site for N₂ adsorption and activation. Co-Cu and Ni-Ru couples show an excellent capacity to surface hydrogenation at a low overpotential. © 2020 Wiley-VCH GmbH.