The in situ GDE cell had a liquid electrolyte reservoir in which the immersion objective was dipped, and the carbon cloth coated with copper catalysts separated the electrolyte reservoir and the gas channel. CO2 was continuously delivered to the catalyst at a flow rate of 10 sccm. The counter electrode, a glassy carbon rod, and the reference electrode, Ag/AgCl, were dipped in the electrolyte reservoir around 0.5 cm away from the cathode. After purging the CO2 into the electrolyte for more than 15 min, we acquired a spectrum of open circuit to observe the surface species prior to electrochemical reaction. Then, a constant potential was applied, to observe the species during the static electrolysis. In the following step, we applied pulsed electrolysis conditions one by one. Electrochemical parameters were the same as described above. 1M KOH was used as electrolyte, with the presence or absence of 1.5 M NH4OH to identify the peaks associated with C-N bond. In addition, the different electrolysis condition (static electrolysis and pulsed electrolysis) were compared to observe the difference in surface intermediates.