Bismuth-Based Electrocatalysts for Identical Value-Added Formic Acid Through Coupling CO₂ Reduction and Methanol...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical CO2 reduction (CO2RR) is key for reducing atmospheric CO2.
• The oxygen evolution reaction (OER) coupled with CO2RR is energy-intensive.
• Methanol oxidation reaction (MOR) presents an alternative anode reaction for CO2RR.

Purpose of the Study:

• To develop an efficient coupled system for formate co-production using CO2RR and MOR.
• To investigate the role of oxygen vacancies and heteroatom doping in enhancing catalytic activity.
• To compare the energy efficiency of CO2RR//MOR with CO2RR//OER.

Main Methods:

• Synthesis of Bi/Bi2O3 and Ni-Bi(OH)3 electrocatalysts.
• Electrochemical characterization of CO2RR and MOR performance.
• Density Functional Theory (DFT) calculations to understand reaction mechanisms.

Main Results:

• The coupled CO2RR//MOR system achieved formate production with significantly lower energy input (7.26 kWh/gformate) than CO2RR//OER (13.67 kWh/gformate).
• Bi/Bi2O3 demonstrated high formate Faradaic efficiency (>80%) for CO2RR over a wide potential range.
• Ni-Bi(OH)3 showed excellent formate Faradaic efficiency (>98%) for MOR.
• The two-electrode system exhibited remarkable stability, operating for over 250 hours with sustained high Faradaic efficiency.

Conclusions:

• Coupling CO2RR with MOR using engineered Bi/Bi2O3 and Ni-Bi(OH)3 catalysts is an energy-efficient strategy for formate co-production.
• Oxygen vacancies in Bi/Bi2O3 enhance OCHO* adsorption, while Ni-Bi(OH)3 lowers the energy barrier for MOR's rate-determining step.
• This approach offers a promising alternative to traditional CO2RR//OER systems, reducing energy consumption and enabling valuable chemical synthesis.