Active and conductive layer stacked superlattices for highly selective CO₂ electroreduction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Metal oxides are common electrocatalysts for CO2 reduction but suffer from self-reduction, hindering selectivity.
• Self-reduction of catalysts leads to increased hydrogen evolution and reduced CO2 electroreduction efficiency.

Purpose of the Study:

• To design a novel superlattice structure that protects active metal oxide electrocatalysts from self-reduction.
• To enhance the selectivity and efficiency of CO2 electroreduction to formate.
• To investigate the protective mechanism of metal selenide layers in superlattice structures.

Main Methods:

• Fabrication and characterization of BiCuSeO superlattices.
• Electrochemical testing for CO2 reduction reaction (CO2RR).
• X-ray photoelectron spectroscopy (XPS) to analyze oxidation states.
• Density functional theory (DFT) calculations to understand reaction mechanisms.

Main Results:

• BiCuSeO superlattices demonstrated high stability, with the active [Bi2O2]2+ sublayers preventing self-reduction.
• Rapid electron transfer through the conductive [Cu2Se2]2- sublayer protected the oxide layer.
• Over 90% formate selectivity was achieved across a wide potential range (-0.4 to -1.1 V).
• DFT calculations revealed enhanced activity due to Bi p-O p orbital overlap in the OCHO* intermediate.

Conclusions:

• The proposed superlattice model effectively protects metal oxide electrocatalysts from self-reduction.
• BiCuSeO superlattices offer a promising strategy for highly selective CO2 electroreduction to formate.
• This work provides a new avenue for improving CO2 electroreduction catalysts based on metal oxide systems.