Modulating the local microenvironment over isolated nickel sites through first-shell coordination to regulate the...

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Controlling product selectivity in CO2 electroreduction is vital for efficient catalysis.
• Theoretical studies suggest modifying the coordination structure of isolated Ni sites can promote CH4 production, but experimental validation is lacking.

Purpose of the Study:

• To experimentally demonstrate the transformation of CO2 electroreduction products from CO to CH4 by manipulating the local microenvironment of single-atom Ni catalysts.
• To investigate the role of boron coordination in the Ni-N-C structure on catalytic performance and reaction pathways.

Main Methods:

• Synthesis of single-atom Ni catalysts with controlled boron coordination environments.
• Electrochemical CO2 reduction experiments.
• In situ characterization techniques.
• Density functional theory (DFT) calculations.

Main Results:

• Regulating the boron coordination shell around Ni sites successfully shifted the product selectivity from CO to CH4.
• Boron in the second shell (Ni-N4-B/C) favored CO formation.
• Incorporating boron into the first shell (Ni-N3B1/C) significantly altered the electronic structure of Ni, enhancing CO intermediate adsorption and promoting CH4 as the dominant product.

Conclusions:

• This study provides the first experimental evidence for electrochemical CO2-to-CH4 conversion using isolated Ni sites.
• The findings highlight the critical importance of precisely controlling the local coordination environment of single-atom catalysts to steer reaction pathways and achieve desired product selectivity.