Red Carbon Mediated Formation of Cu 2 O Clusters Dispersed on the Oxocarbon Framework by Fehling's Route and their Use for the Nitrate Electroreduction in Acidic Conditions.

The oligomers of carbon suboxide, known as red carbon, exhibit a highly conjugated structure and semiconducting properties. Upon mild heat treatment, it transforms into a carbonaceous framework rich in oxygen surface terminations, called oxocarbon. In this study, the abundant oxygen functionalities are harnessed as anchors to create oxocarbon-supported nanohybrid electrocatalysts. Starting with single atomic Cu (II) strongly coordinated to oxygen atoms on red carbon, the Fehling reaction leads to the formation of Cu 2 O clusters. Simultaneously, a covalent oxocarbon framework emerges via cross-linking, providing robust support for Cu 2 O clusters. Notably, the oxocarbon support effectively stabilizes Cu 2 O clusters of very small size, ensuring their high durability in acidic conditions and the presence of ammonia. The synthesized material exhibits a superior electrocatalytic activity for nitrate reduction under acidic electrolyte conditions, with a high yield rate of ammonium (NH 4 + ) at 3.31 mmol h -1  mg cat -1 and a Faradaic efficiency of 92.5% at a potential of -0.4 V (vs RHE).