Nickel Single Atom Density-Dependent CO₂ Efficient Electroreduction.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Transition metal-nitrogen-carbon (M-N-C) materials with M-N-x sites show promise for CO2 electroreduction (CO2RR).
• A clear understanding of how metal single-atom density affects CO2RR performance is needed.

Purpose of the Study:

• To investigate the relationship between nickel single-atom density and CO2RR performance.
• To design and synthesize Ni single-atom catalysts (SACs) on N-doped carbon supports.

Main Methods:

• Fabrication of Ni SACs on N-doped graphene-like carbon (Ni1@NG-900) with varying Ni loadings.
• Tuning the density of Ni single atoms (DNi) from 0.01 to 1.19 atoms nm-2.
• Electrochemical evaluation of CO2RR performance, including Faradaic efficiency for CO (FE_CO).

Main Results:

• FE_CO increased from 13.4% to 96.2% as DNi rose from 0 to 0.068 atoms nm-2.
• Further increases in DNi (up to 1.19 atoms nm-2) resulted in a marginal FE_CO improvement to 98.2%.
• Theoretical calculations supported the experimental findings, revealing a trade-off relationship.

Conclusions:

• The density of Ni single atoms is a critical factor influencing CO2RR performance in M-N-C catalysts.
• Optimizing DNi is essential for maximizing the efficiency of CO2RR for C1 product synthesis.
• This study provides insights into rational catalyst design for improved CO2 electroreduction.