NiO Nanodots on Graphene for Efficient Electrochemical N2 Reduction to NH3

Current artificial NH3 synthesis relies heavily on the Haber–Bosch process that involves enormous energy consumption and huge CO2 emission. The electrochemical N2 reduction reaction (NRR) offers an eco-friendly and sustainable alternative but demands cost-effective and efficient NRR electrocatalysts. Herein, NiO nanodots (∼2 nm) supported on graphene (NiO/G) were developed as a high-performance NRR electrocatalyst at ambient conditions. Electrochemical tests indicated that the NiO/G exhibited a high NH3 yield (18.6 μg h–1 mg–1) and Faradaic efficiency (7.8%) at −0.7 V vs reversible hydrogen electrode, outperforming the most reported NRR electrocatalysts. Experimental and density functional theory (DFT) results revealed that NiO was the dominating active center, and nanodot structure enabled the NiO to expose more active sites. DFT results further demonstrated that the distal associative route was the preferable NRR pathway with *N2 → *NNH being the rate-determining step.