Ion-regulated electrochemical double layer drives highly selective CO₂-to-C₂₊ conversion

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The electrochemical double layer (EDL) at the catalyst-electrolyte interface is crucial for electrocatalytic CO2 reduction (eCO2RR) but is often overlooked.
• Research has focused on active site engineering for multi-carbon (C2+) products, with less attention on EDL regulation.
• Understanding the interplay between catalyst design and EDL is key to improving eCO2RR efficiency.

Purpose of the Study:

• To develop a Na+-assisted surface engineering strategy for Cu2O catalysts.
• To precisely tailor the interfacial microenvironment of grain-boundary-rich Cu2O.
• To investigate how EDL modulation influences C2+ product formation in eCO2RR.

Main Methods:

• Utilized alkaline etching and thermal treatment to modify Cu2O catalyst surfaces.
• Employed Na+ anchoring on catalyst surfaces to create a specific interfacial microenvironment.
• Conducted in situ spectroscopic analyses to study surface species and EDL characteristics.

Main Results:

• Na+ successfully anchored on the Cu2O surface, preserving intrinsic active sites.
• The engineered surface promoted hydroxyl species accumulation, creating a local alkaline microenvironment within the EDL.
• Achieved high C2+ selectivity (∼90% at 250 mA cm-2 and ∼75% at 400 mA cm-2) across a wide current density range.

Conclusions:

• Surface structural modification is an effective strategy to modulate the EDL.
• Tailoring the interfacial microenvironment via EDL regulation enhances C2+ product formation in eCO2RR.
• Na+-assisted engineering offers a promising route for efficient electrocatalytic CO2 conversion to valuable multi-carbon products.