No abstract

Electrochemical reduction of carbon dioxide (CO 2 ) to formate is energetically inefficient because a high overpotential (>1.0 V) is required for most traditional catalysts. In this work, Bi 2 O 2 CO 3 (BOC) nanosheets were synthesized as electrocatalysts of CO 2 reduction for the first time. Additionally, BOC decorated on the glassy carbon electrode was reduced in situ to metal Bi (RB) for comparing the catalytic performance toward CO 2 reduction to that of BOC. The maximum faradaic efficiency of BOC was 83% at an overpotential of 0.59 V, which is a little lower than that of RB (90% obtained at the overpotential of 0.99 V). However, the overpotential for the reduction of CO 2 to formate on BOC is obviously decreased compared to that on RB. After 27 h of electrolysis, approximately 80% formate selectivity was obtained using the BOC catalyst. According to the experimental results and the related literature, a new mechanism for the CO 2 reduction reaction on BOC was proposed, which may play a guiding role in future catalyst design.

Carbon dioxide (CO 2 ) can be reduced to valuable chemicals under the suitable cathode potential. During the electrochemical reduction of CO 2 , most metal oxide catalysts will be reduced to zero valent metals. In this work, flower-like Bi 2 O 3 precursor has been prepared by the method of hydrothermal synthesis, and it has become pure Bi 2 O 3 with irregularly shape after calcination at 500 °C for 2 h. The precursor and Bi 2 O 3 have been in situ reduced on the glass carbon electrodes separately, then they are used as the electrocatalysts for CO 2 reduction. The faradaic efficiencies for producing formate on the two electrocatalysts are all up to 82% at a low overpotential of 0.89 V. The electrocatalyst reduced from the precursor possesses larger current density for CO 2 reduction than that reduced from Bi 2 O 3 , and it is believed to be a promising catalyst for further application.