Near-Unity Selectivity Inversion Between CO₂ Electroreduction and H₂ Evolution via Atomic Coordination Editing.

Area of Science:

• Electrocatalysis
• Materials Science
• Surface Chemistry

Background:

• Tuning catalyst selectivity is crucial for targeted chemical transformations.
• Single-atom catalysts (SACs) offer precise control over active sites.
• Achieving near-unity selectivity inversion between competing reactions remains a challenge.

Purpose of the Study:

• To demonstrate atomic coordination editing of NiN4-based SACs for selective CO2 reduction (CO2RR) or H2 evolution (HER).
• To investigate the mechanism of selectivity switching through structural modification.
• To achieve high-performance electrocatalysis for CO2RR.

Main Methods:

• Theoretical calculations to guide catalyst design.
• Synthesis and characterization of NiN4 and NiN3C single-atom catalysts.
• Electrochemical performance testing (Faradaic efficiency, current density, energy efficiency).
• In situ ATR-SEIRAS and charge-density analysis for mechanistic studies.

Main Results:

• NiN4 exclusively catalyzes HER, while NiN3C achieves ~99% CO selectivity in CO2RR.
• NiN3C exhibits high partial current density (~840 mA cm-2), carbon energy efficiency (77%), and turnover frequency (6.03 × 10^5 h-1).
• Mechanistic studies reveal NiN3C weakens Ni-centered σ interactions and enhances C-centered π coupling with intermediates, shifting adsorption sites.

Conclusions:

• Atomic coordination editing of NiN4 to NiN3C effectively switches electrocatalytic selectivity.
• The NiN3C catalyst demonstrates superior performance and stability for CO2RR.
• This strategy provides mechanistic insights into catalytic pathway control and enables high-performance electrocatalysis.