Time-resolved Observation of Surface-Bound Carbon Dioxide Radical Anions on Metallic Nanocatalyst

Abstract Time-resolved identification of surface-bound intermediates on metallic nanocatalysts is imperative to develop an accurate understanding of the elementary steps of CO2 reduction, but remains challenging in particular for carbon dioxide radical anions, CO2•‒. Herein, we use pulse radiolysis to observe the holistic stabilization process of CO2•‒ radicals on well-defined nanoscale metallic sites. The method allows to identify surface-bound intermediates with characteristic transient absorption and the distinct kinetics for three typical metallic nanocatalysts (Cu, Au, and Ni). The interfacial interactions were further investigated by varying the important factors, such as catalyst size and cation in the electrolyte. The spectral data, combined with molecular simulations, highlighted the selectivity of the critical initial step in the CO2 catalytic reduction mechanism, even before CO2•‒ radical dissociation.