Optimizing Cu doping on carbon nitrogen holly shell for enhanced selectivity towards formate in CO₂ reduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis
• Sustainable Chemistry

Background:

• Electrochemical carbon dioxide reduction (ECO₂RR) offers a pathway to valuable products and carbon cycle management.
• Catalyst structural instability (reorganization and agglomeration) during ECO₂RR hinders performance.
• Controlling metal doping forms in catalysts is crucial for selectivity.

Purpose of the Study:

• To synthesize and characterize a copper-doped carbon-nitrogen (CNCu) shell catalyst using SiO₂ as a template.
• To investigate how different forms of copper doping (single-atoms vs. clusters) influence catalyst selectivity in ECO₂RR.
• To elucidate the underlying mechanisms governing selectivity differences using DFT calculations.

Main Methods:

• Synthesis of CNCu shell catalysts using a SiO₂ template.
• Electrochemical characterization of catalysts for ECO₂RR performance (Faraday efficiency, potential).
• Density Functional Theory (DFT) calculations to analyze reaction mechanisms and intermediate binding energies.

Main Results:

• The CNCu_2.5 catalyst (single-atom Cu doping) achieved 85% Faraday efficiency for formate at -0.9 V vs. RHE.
• The CNCu₂₅ catalyst (coexisting Cu clusters and single-atoms) favored multi-carbon products, yielding 45% for ethanol and 23% for acetic acid.
• DFT revealed Cu single-atoms promote formate production, while combined Cu species favor multi-carbon products by altering HCOO* adsorption and pathway energy.

Conclusions:

• Precise control over metal doping form in MCN catalysts is a key strategy for tuning ECO₂RR selectivity.
• Single-atom copper doping enhances formate selectivity, while mixed Cu species promote multi-carbon product formation.
• This work provides fundamental insights into catalyst design for efficient and selective electrochemical CO₂ conversion.