Leveraging Intermediates for Selective Acidic CO₂-to-CH₄ Electroreduction via Synergistic Cu-Based Single Atoms and...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical CO2 reduction reaction (CO2RR) to methane (CH4) is crucial for a carbon-neutral future.
• Achieving high selectivity in acidic electrolytes is challenging due to the competing hydrogen evolution reaction and CO intermediate side reactions.
• Optimizing the hydrogenation of CO intermediates (*CO) with hydrogen (*H) is key for selective CO2-to-CH4 electroreduction.

Purpose of the Study:

• To develop a synergistic copper-based catalyst for efficient and selective CO2 electroreduction to CH4 in acidic media.
• To investigate the role of dual-functional sites in controlling reaction pathways and enhancing CH4 production.
• To demonstrate the catalyst's performance across a range of pH conditions.

Main Methods:

• Synthesis of a synergistic Cu-based catalyst (Cu1+SNs) on mesoporous silica (SBA-15).
• The catalyst features isolated Cu single atoms (Cu1-SAs) and ensembled CuO(x) sub-nanoparticles (CuO(x)-SNs).
• Electrochemical evaluation of CO2RR performance, including Faradaic efficiency and selectivity, in acidic electrolytes.

Main Results:

• The Cu1+SNs catalyst achieved a high Faradaic efficiency of 70.4% for CO2-to-CH4 electroreduction in acidic electrolyte.
• CuO(x)-SNs activated CO2 and inhibited CO dimerization, while Cu1-SAs facilitated water dissociation for CO hydrogenation.
• The catalyst demonstrated robust and high selectivity (>70%) for CH4 production across acidic, neutral, and alkaline electrolytes.

Conclusions:

• The synergistic effect between isolated Cu single atoms and CuO(x) sub-nanoparticles enables efficient CH4 generation via CO2RR.
• This catalyst design overcomes selectivity limitations in acidic electrolytes by optimizing intermediate hydrogenation.
• The developed catalyst offers a promising pathway for designing structurally heterogeneous catalysts for selective multi-step reactions.