Regulating the selectivity through ionomer–catalyst interactions for high-efficiency electrocatalytic CO2 reduction

Establishing a suitable electrode microenvironment is important to achieving high-efficiency electrocatalytic CO2 reduction at industrially relevant current densities. Introducing ionomers provided an effective method for regulating the electrode microenvironment, but the mechanism of interactions between the ionomer and the catalyst remains elusive. In this work, the influence of three types of ionomers on the performance and microenvironment of Ag nanoparticle (NP) and molecularly dispersed cobalt phthalocyanine (CoPc MDE) catalysts were systematically investigated. It was found that the non-covalent interactions between the ionomers with aromatic groups and CoPc MDE resulted in the hydrophilicity of electrode and undesirably promoted the generation of hydrogen during the reaction. The optimal ionomer–catalyst combinations achieved excellent FE(CO)s > 99% at current densities up to −200 mA cm−2 and stable operation for more than 180 h at a current density of −100 mA cm−2. This work underlines the necessity of selecting appropriate ionomer according to the nature of catalyst.