Modulating Electronic Density of Single-Atom Ni Center by Heteroatoms for Efficient CO₂ Electroreduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) offer unique properties for chemical reactions.
• Controlling the electronic structure of metal centers in SACs is crucial for enhancing catalytic activity.
• Electrochemical CO2 reduction (CO2RR) is a key process for sustainable energy solutions.

Purpose of the Study:

• To systematically tailor the electronic structure of Ni centers in Ni1-NC SACs.
• To investigate the effect of incorporating electron-rich phosphorus or electron-deficient boron on CO2RR performance.
• To establish a quantitative relationship between electronic structure and catalytic efficiency.

Main Methods:

• Synthesis of Ni1-NC, Ni1-PNC, and Ni1-BNC single-atom catalysts.
• Electrochemical characterization, including current density and Faradaic efficiency measurements.
• Density Functional Theory (DFT) calculations and detailed characterizations.

Main Results:

• The Ni1-PNC catalyst with a Ni1-N3P site demonstrated superior CO2RR performance.
• Achieved a current density of 14.6 mA cm-2 and 90.6% Faradaic efficiency for CO production at -0.8 V vs RHE.
• Identified a linear correlation between the valence state of Ni and CO2RR performance.
• Phosphorus incorporation localized electrons at the Ni1 center, enhancing CO2 adsorption and *COOH intermediate formation.

Conclusions:

• Phosphorus incorporation is an effective strategy for modulating the electronic structure of single-atom catalysts.
• The Ni1-PNC catalyst shows significant potential for efficient electrochemical CO2 reduction.
• This study provides a quantitative approach for designing high-performance single-atom catalysts.