Controllable Assembly of Highly Oxidized Cobalt on Graphdiyne Surface for Efficient Conversion of Nitrogen into Nitric Acid

The manufacture of nitric acid (HNO3) consumes large amounts of energy and causes serious environmental pollution. Electrochemical synthesis is regarded as a key way to eliminate carbon emissions from the chemicals industry. The selective electrosynthesis of HNO3 from nitrogen was achieved by controllable assembly of cobalt metal on graphdiyne surface using a powerful tool of electrochemistry at ambient conditions. As an advanced material, graphdiyne (GDY) has a large conjugated structure on its surface and is rich in sp-C triple bond skeleton, which can achieve strong interaction with metal atoms, resulting in incomplete charge transfer between graphdiyne and cobalt atoms. The experimental and theoretical calculation results show that the highly oxidized cobalt on graphdiyne (HOCo/GDY) can selectively and efficiently activate and convert the nitrogen into the key intermediate *NO, which promotes the efficient overall conversion performance of nitrogen to nitric acid. Thus, the highest nitric acid yield (192.0 mu g h-1 mg-1) and Faradaic efficiency (21.5 %) were achieved at low potentials. Through the incorporation highly oxidized metal species in C(sp)-rich graphdiyne, nitrogen can selectively and efficiently be converted into *NO, the key intermediate towards nitric acid synthesis. In summary, nitrogen is converted into nitric acid in high yield and good Faraday efficiencyimage