Temperature-Dependent CO₂ Electroreduction over Fe-N-C and Ni-N-C Single-Atom Catalysts

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Electrochemical CO2 reduction (CO2 RR) is crucial for sustainable chemical production.
• Reaction temperature significantly influences CO2 RR selectivity and activity, competing with hydrogen evolution reaction (HER).
• Fe-N-C and Ni-N-C single-atom catalysts are promising for CO2 RR.

Purpose of the Study:

• Investigate the temperature-dependent performance of Fe-N-C and Ni-N-C single-atom catalysts for CO2 RR.
• Understand how temperature variations affect CO selectivity and current density.
• Elucidate the underlying mechanisms responsible for catalyst performance differences.

Main Methods:

• Electrochemical CO2 reduction reaction (CO2 RR) experiments conducted over a temperature range of 303–343 K.
• Analysis of CO Faradaic efficiency and current density.
• Temperature programmed desorption (TPD) and density functional theory (DFT) calculations.

Main Results:

• Fe-N-C catalysts showed improved CO Faradaic efficiency with increasing temperature, reaching 185.8 mA cm⁻² at 343 K.
• Ni-N-C catalysts exhibited optimal CO current density at 323 K (252.5 mA cm⁻²), decreasing at higher temperatures.
• Temperature-dependent performance variations were attributed to differing adsorption strengths of reaction intermediates.

Conclusions:

• Reaction temperature is a critical parameter for tuning the performance of Fe-N-C and Ni-N-C catalysts in CO2 RR.
• The distinct temperature responses of Fe-N-C and Ni-N-C catalysts stem from variations in intermediate adsorption energies.
• Optimizing temperature is essential for maximizing CO production efficiency and selectivity.