Alkali cation-induced cathodic corrosion in Cu electrocatalysts

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The structural evolution of copper (Cu) catalysts during electrochemical carbon dioxide (CO2) reduction is a known but poorly understood process.
• Understanding catalyst reconstruction is crucial for optimizing CO2 electroreduction technologies.

Purpose of the Study:

• To investigate the structural evolution of Cu nanocubes during CO2 reduction under various reaction conditions.
• To elucidate the mechanism of catalyst reconstruction and its impact on catalytic performance.

Main Methods:

• Identical location transmission electron microscopy (ILTEM)
• Cyclic voltammetry (CV)
• In situ X-ray absorption fine structure (XAFS) spectroscopy
• Ab initio molecular dynamics (AIMD) simulations

Main Results:

• Cu catalysts reconstruct via alkali cation-induced cathodic corrosion at potentials more negative than -0.4 V RHE.
• Alkali cations in the electrolyte are essential for this reconstruction pathway.
• Catalyst reconstruction leads to dynamic morphologies, hindering long-term selectivity and activity enhancement.
• Operating Cu catalysts at less negative potentials preserves Cu nanocube morphology, offering improved selectivity.

Conclusions:

• Alkali cation-induced cathodic corrosion is a critical, previously unexplored pathway for Cu catalyst reconstruction during CO2 electroreduction.
• Dynamic catalyst morphologies resulting from reconstruction limit long-term performance gains.
• Controlling electrode potential and utilizing specific pre-catalyst morphologies, like Cu nanocubes, are key strategies for enhancing CO2 electroreduction stability and selectivity.