Highly Efficient CO₂ Electroreduction in Artificial Seawater Electrolyte Catalyzed by Strong-Acid/Base-Resistant MOF

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Sodium chloride (NaCl) is a cost-effective electrolyte for CO2 electroreduction (CO2RR).
• The hydrogen evolution reaction (HER) is a major challenge in CO2RR using NaCl electrolytes.
• Developing stable and selective catalysts is crucial for efficient CO2RR.

Purpose of the Study:

• To develop a novel catalyst for selective CO2 electroreduction to CO in NaCl electrolytes.
• To investigate the catalyst's stability and performance in various conditions.
• To elucidate the mechanism for suppressing HER and enhancing CO2RR.

Main Methods:

• Synthesis of a novel Zn-MOF {[Zn5(tz)6(HCOO)4]·2H2O}n.
• Electrochemical testing in artificial and natural seawater electrolytes.
• Stability tests in harsh acidic and alkaline conditions.
• Mechanism analysis using micropore interactions with water molecules.

Main Results:

• The Zn-MOF catalyst demonstrated excellent stability in 0.5 M NaCl for 16 weeks and in 9 M HCl and 2 M NaOH.
• High selectivity for CO2 to CO conversion was achieved, with Faradaic efficiencies (FECO) of 94.4% and 91.1% in artificial and natural seawater, respectively.
• The catalyst maintained performance over 20 hours, showing promising industrial potential with a low production cost.

Conclusions:

• The novel Zn-MOF effectively suppresses HER in NaCl electrolytes, enhancing CO2RR selectivity.
• Micropores in the MOF play a key role in inhibiting HER by forming a cationic layer.
• This work presents a viable strategy for designing stable, efficient, and economical catalysts for sustainable CO2 electroreduction.