Theoretical insights into p-block-functionalized carbon edges for efficient electrochemical CO₂ reduction

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Metal-free carbon materials are actively researched as sustainable electrocatalysts for carbon dioxide reduction reaction (CO2RR).
• Understanding the fundamental principles governing the catalytic activity of these materials is crucial for designing efficient catalysts.
• The electronic properties of carbon active sites can be modulated by incorporating heteroatoms, particularly p-block elements.

Purpose of the Study:

• To investigate the role of p-block elements in functionalizing carbon materials for CO2RR.
• To establish design principles for high-performance, metal-free CO2RR electrocatalysts.
• To identify specific functional groups that enhance catalytic activity.

Main Methods:

• Density functional theory (DFT) calculations were employed to study graphene nanoribbon edge models.
• A systematic screening of 14 graphene nanoribbon edge models functionalized with various p-block elements (Edge-X/C) was performed.
• Key electronic descriptors, including the p-band center and surface work function, were analyzed.

Main Results:

• Electronegativity of p-block functional groups significantly tunes the p-band center and work function of carbon atoms.
• A volcano-shaped correlation between the p-band center and CO2RR catalytic activity was identified.
• Moderate orbital energy levels, as seen in Edge-AsH2/C, were found to be optimal, suppressing excessive electron back-donation and facilitating CO desorption.
• Edge-AsH2/C demonstrated the lowest theoretical limiting potential, indicating superior catalytic performance.

Conclusions:

• The electronegativity of p-block elements is a critical parameter for designing effective metal-free CO2RR electrocatalysts.
• Tuning the p-band center through appropriate functionalization is key to optimizing catalytic activity.
• The findings provide a theoretical framework for the rational design of advanced carbon-based electrocatalysts for CO2 reduction.