Efficient electrocatalytic N2 reduction on CoO quantum dots

Abstract

Electrocatalytic conversion of N₂ to NH₃via the N₂ reduction reaction (NRR) provides a sustainable avenue for large-scale NH₃ production. However, it remains challenging to develop effective and durable NRR catalysts to promote the NH₃ synthesis rate and faradaic efficiency (FE). Here, combining theoretical predictions and experimental verifications, we showed that the CoO nanostructures could be a new class of highly efficient NRR catalysts. Density functional theory calculations revealed that CoO possessed poor HER activity but favorable NRR activity. When supporting CoO quantum dots (QDs, 2–5 nm) on reduced graphene oxide (RGO), the resulting CoO QD/RGO exhibited a high NH₃ yield of 21.5 μg h⁻¹ mg⁻¹ and an FE of 8.3% at −0.6 V vs. the reversible hydrogen electrode under ambient conditions, superior to most of the reported NRR catalysts. Furthermore, the CoO QD/RGO showed excellent selectivity and stability, demonstrating the great potential of Co-based catalysts for electrocatalytic synthesis of NH₃.