Decoration of copper foam with Ni nanorods and copper oxide nanosheets to produce a high-stability electrocatalyst for the reduction of CO2:Characterization of the electrosynthesis of isonicotinic acid

摘要

CuOeCu2O(CuxO)nanosheets were coated on a copper foam substrate by the electrochemical anodization method in an alkaline solution.Constant current coulometry was performed to electrodeposit Ni nanorods on the surface of a Cu/CuxO electrode.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)proved that the copper oxide nanosheets were anchored on the copper foam substrate and modified by Ni nanorods(Cu/CuxO/Ni).The process took place via a facile and inexpensive electrodeposition method.As the results indicate,owing to the synergistic effect of adjacent CuxO and Ni sites,a Cu/CuxO/Ni electrode has a very good and stable electrocatalytic activity to reduce CO2.As tested in this study,the product of the electrocatalytic reduction of CO2(i.e.activated CO2,or CO_2~(·-))can be used for the electrocarboxylation of pyridine in mild conditions.Once an electron is transferred from CO_2~(·-)to pyridine,a pyridine radical anion is formed.Based on the EC'C0CC mechanism,this radical anion reacts with CO_2~(·-)and produces isonicotinic acid as the main product.In addition,two pyridine radical anions react together and produce a 4,4'-bipyridine dimer.The high stability of the electrocatalyst during the electrolysis process and the simplicity of the workup make the proposed modified electrode appropriate for the electrosynthesis of some organic compounds.