pH-Universal Electrocatalytic CO₂ Reduction with Ampere-Level Current Density on Doping-Engineered Bismuth Sulfide.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic CO2 reduction to formic acid faces challenges in CO2 activation and pH-dependent performance.
• Developing efficient and stable catalysts is crucial for practical applications.

Purpose of the Study:

• To engineer a doping-modified bismuth sulfide catalyst for enhanced CO2 electroreduction to formic acid.
• To achieve high performance and stability across a wide pH range.

Main Methods:

• Synthesis of a doping-engineered bismuth sulfide pre-catalyst (BiS-1).
• Electrochemical characterization including Faraday efficiency and current density measurements in flow cells and membrane electrode assemblies.
• In situ spectroscopy and density functional theory (DFT) calculations to elucidate the catalytic mechanism.

Main Results:

• The BiS-1 catalyst, after electrochemical reconstruction, demonstrated ultrahigh performance for CO2RR to formate/formic acid across neutral, alkaline, and acidic conditions.
• Achieved a Faraday efficiency (FE) of ~95% at 2000 mA cm-2 in neutral/alkaline solutions and ~95% FE across 100-1300 mA cm-2 in acidic solutions.
• Demonstrated stable operation for 150 hours at 200 mA cm-2 in a membrane electrode assembly electrolyzer.

Conclusions:

• Sulfur doping in bismuth modulates electronic structure, promoting formate intermediate formation for efficient CO2RR.
• The developed BiS-1 catalyst offers a promising pathway for sustainable and efficient production of formate/formic acid.