Efficient electrolyzer for CO2 splitting in neutral water using earth-abundant materials.

Area of Science:

• Electrochemistry
• Catalysis
• Renewable Energy

Background:

• Efficient electrochemical splitting of carbon dioxide (CO2) is crucial for renewable energy storage and CO2 utilization as a chemical feedstock.
• Development of heterogeneous catalysts for efficient CO2 reduction coupled with oxygen evolution is needed.

Purpose of the Study:

• To develop a low-cost, high-energy-efficiency electrochemical cell for CO2 to CO and O2 conversion.
• To demonstrate the feasibility of associating a molecular catalyst with an anodic catalyst for CO2 splitting.

Main Methods:

• An iron porphyrin cathode immobilized on a Nafion/carbon powder layer was used for CO2 reduction.
• A phosphate cobalt oxide anode was employed for water oxidation.
• A home-made electrolyzer with a Nafion membrane was utilized for the electrochemical cell.

Main Results:

• The electrochemical cell achieved 90% faradaic efficiency for CO production in neutral water.
• A cell voltage of 2.5 V yielded current densities of approximately 1 mA/cm(2) over 30 hours.
• The system demonstrated 50% energy efficiency for splitting CO2 and H2O into CO and O2, with CO2 reduction exceeding water reduction.

Conclusions:

• An efficient, low-voltage electrochemical cell for CO2 to CO and O2 conversion was successfully demonstrated.
• The cell utilizes an abundant transition metal-based molecular catalyst and a cost-effective anodic catalyst.
• Stable operation with high proton transport efficiency and stable pH was achieved.