Tunable Ag Micromorphologies Show High Activities for Electrochemical H2 Evolution and CO2 Electrochemical Reduction

Contaminate-free nanostructured Ag is prepared from electrochemical redox-treated Ag by two different potential pulses (DP and r-DP) in an NaBr aqueous solution. Agr-Dp and Ag-DP from r-DP and DP, respectively, are easily tuned for their activities in the hydrogen evolution reaction (HER) favoring or selective CO2 reduction reaction (CO2RR). Agr-Dp shows Pt-like HER activity in H(2)SO(4 )aqueous solution, and Ag-Dp is capable of electrochemically reducing CO2 to CO with approximately 97.8% catalytic selectivity at a low overpotential of similar to 0.25 V in NaHCO3 aqueous solution. The electrochemical signals for the first observed CO2 center dot- intermediate adsorption (CO2ads center dot-) and HCO3- adsorption (HCO3ads-) in the selected NaClO4 aqueous solution were used to understand the possible role of HCO3- in CO2RR.