The upper boundary of 60 min was chosen based on literature-reported chronoamperometry data exhibiting a clear trend of decreasing CO2RR activity of various copper surfaces on this timescale by multiple authors. 7 , 11 , 21 , 32 , 33 Blank cyclic voltammograms (0.1 M NaOH) obtained prior to and after extended cathodization periods in either 10 M NaOH or 0.5 M KHCO 3 are depicted in Figure 4 , where close-ups of relevant regions are provided as insets and trends discussed in text are denoted by arrows.
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