Revealing Single-Atom-Site-Density-Driven Kinetic Resolution in Acidic CO₂ Electroreduction

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Acidic electrochemical CO2 reduction to CO is promising for carbon efficiency.
• Hydrogen evolution competes kinetically in proton-rich environments, limiting CO2 reduction.
• Controlling pathway competition is crucial for efficient electrosynthesis.

Purpose of the Study:

• Investigate the role of single-atom site density in resolving pathway competition.
• Develop nickel single-atom catalysts for efficient CO2 reduction.
• Understand the mechanism of CO2 reduction enhancement.

Main Methods:

• High-throughput synthesis and screening of nickel single-atom catalysts with tunable site densities.
• In situ scanning electrochemical microscopy and infrared spectroscopy.
• Theoretical investigations of electronic structure and reaction pathways.

Main Results:

• Increased single-atom site density significantly boosted CO partial current density to 640 mA cm-2.
• Faradaic efficiency for CO production exceeded 95%.
• Evidence of preferential promotion of the *COOH-mediated CO2 hydrogenation pathway was observed.

Conclusions:

• Single-atom site density is a critical descriptor for pathway competition in CO2 reduction.
• Inter-site electronic coupling modifies local electronic structure and reaction energetics.
• Provides a framework for directing interfacial reactions in single-atom catalysis.