Electrochemical CO2 reduction to CO facilitated by reduced boron-doped diamond

In the mechanistic investigations of electrochemical CO2 reduction reaction (eCO2RR), the undercoordinated site and oxidized metals are generally considered the most likely sources of catalytic sites. However, in the eCO2RR on boron-doped diamond (BDD) electrodes, metal centers are not available, and undercoordinated sites from boron doping did not demonstrated a favorable effect on the catalytic activity. By means of electrochemical activation, we found that when the surface of BDD electrodes is in a stable reduced state, the catalytic activity of eCO2RR for CO production is optimal. The Faradaic efficiency for CO production was increased up to 64 %, and the corresponding production rate reached 23 μmol cm−2 h−1, which was more than three times of the non-activated BDD set as comparison. This work demonstrates that the catalytic activity for eCO2RR can also originate from a reduced surface of BDD electrode.