Impurity Ion Complexation Enhances Carbon Dioxide Reduction Catalysis

Herein, we show that group 11 CO2 reduction catalysts are rapidly poisoned by progressive deposition of trace metal ion impurities present in high purity electrolytes. Metal impurity deposition was characterized by XPS and in situ stripping voltammetry and is coincident with loss of catalytic activity and selectivity for CO2 reduction, favoring hydrogen evolution on poisoned surfaces. Metal deposition can be suppressed by complexing trace metal ion impurities with ethylenediaminetetraacetic acid or solid-supported iminodiacetate resins. Metal ion complexation allows for reproducible, sustained catalytic activity and selectivity for CO2 reduction on Au, Ag, and Cu electrodes. Together, this study establishes the principal mode by which group 11 CO2 reduction catalysts are poisoned and lays out a general approach for extending the lifetime of electrocatalysts subject to impurity metal deposition.