A New Hexagonal Cobalt Nanosheet Catalyst for Selective CO₂ Conversion to Ethanal

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Carbon dioxide reduction reaction (CO2RR) is crucial for sustainable chemical synthesis.
• Developing selective catalysts for CO2RR to valuable products like ethanal remains a challenge.

Purpose of the Study:

• To report a novel catalyst based on ferromagnetic hexagonal-close-packed (hcp) cobalt (Co) nanosheets (NSs) for selective CO2RR to ethanal (CH3CHO).

Main Methods:

• Electrochemical reduction of CO2 using hcp Co NSs as catalysts.
• Varying reduction potentials from -0.2 to -1.0 V (vs RHE) in 0.5 M KHCO3 solution.
• Density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• hcp Co NSs selectively produced ethanal as the major product across all tested potentials.
• At -0.4 V, Faradaic efficiency (FE) for ethanal reached 60% with a current density of 5.1 mA cm-2 and mass activity of 3.4 A g-1.
• Total FE for ethanal, ethanol, and methanol was 82%.

Conclusions:

• The hcp Co catalyst demonstrates high selectivity for CO2RR to ethanal.
• DFT calculations indicate intralayer electron transfer promotes [OC-CO]* coupling and suppresses complete hydrogenation, leading to selective CH3CHO formation.