Amine-Functionalized Carbon Nanodot Electrocatalysts Converting Carbon Dioxide to Methane

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Carbon dioxide (CO2) conversion to methane (CH4) is crucial for carbon capture and utilization, offering a pathway for fuel and hydrogen storage.
• Developing efficient and selective electrocatalysts for CO2-to-CH4 conversion remains a significant challenge.

Purpose of the Study:

• To present a molecular tuning strategy using in-situ amine functionalization of nitrogen-doped graphene quantum dots (GQDs) for enhanced CO2-to-CH4 conversion.
• To investigate the relationship between catalyst structure (amine content, pyridinic N) and CO2 conversion products (CH4 and C2).

Main Methods:

• Synthesis of amine-functionalized nitrogen-doped graphene quantum dots (GQDs).
• Electrochemical testing of GQDs for CO2 reduction reaction (CO2RR).
• Analysis of methane (CH4) and C2 product selectivity and efficiency using Faradic efficiency (FE).
• Systematic analysis correlating CH4 yield and C2 production with functional group content.

Main Results:

• Amine-functionalized nitrogen-doped GQDs achieved high CH4 Faradic efficiencies (FE) of 63% and 46% at significant current densities.
• The performance of these GQDs rivals or surpasses state-of-the-art copper-based electrocatalysts.
• A maximum FE of approximately 10% was observed for C2 products, primarily ethylene and ethanol.
• CH4 yield showed a linear correlation with amine group content, while C2 production depended on pyridinic N content.

Conclusions:

• In-situ amine functionalization of nitrogen-doped GQDs is an effective strategy for highly efficient CO2-to-CH4 conversion.
• The study provides insights into catalyst design for achieving industrially relevant CO2-to-CH4 conversion efficiencies.
• This work advances the development of carbon-based electrocatalysts for sustainable energy applications.