Efficient electrocatalytic N2 reduction on CoO quantum dots†
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.