Stabilizing Undercoordinated Zn Active Sites through Confinement in CeO₂ Nanotubes for Efficient Electrochemical CO₂...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Zinc-based catalysts offer a sustainable alternative to noble metals for CO2 reduction reaction (CO2 RR).
• Undercoordinated Zn (Znδ+) sites are hypothesized to be active sites for CO production by optimizing *COOH intermediate binding.
• Limited research exists on the dynamic behavior and stability of Znδ+ sites during CO2 RR.

Purpose of the Study:

• To investigate the role of Znδ+ sites in CO2 reduction.
• To develop stable and highly selective catalysts for CO production.
• To explore the use of CeO2 nanotubes for stabilizing Znδ+ species.

Main Methods:

• Synthesis of ZnO, Znδ+/ZnO, and Zn catalysts by varying reduction potentials.
• Electrochemical characterization and CO2 reduction performance evaluation.
• Theoretical calculations to understand reaction mechanisms and site activity.
• Fabrication of a Znδ+/ZnO/CeO2 catalyst using CeO2 nanotubes.

Main Results:

• Znδ+ sites were found to suppress competing hydrogen evolution reaction (HER) and HCOOH production, favoring CO generation.
• Znδ+/ZnO exhibited higher CO selectivity (70.9% Faradaic efficiency for CO, FE_CO) at -1.48 V vs. RHE compared to pure Zn and ZnO.
• The novel Znδ+/ZnO/CeO2 catalyst achieved an FE_CO of 76.9% at a lower potential (-1.08 V vs. RHE) and maintained selectivity over 18 hours.

Conclusions:

• Undercoordinated Zn sites are crucial for enhancing CO selectivity in CO2 reduction.
• CeO2 nanotubes effectively stabilize Znδ+ species, leading to improved catalytic performance and durability.
• The developed Znδ+/ZnO/CeO2 catalyst represents a significant advancement in efficient and stable CO2 conversion to CO.