Carbon Nanogrid-Directed Interfacial Electric Field Engineering Boosts Selective CO₂-to-Formate Electrosynthesis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis
• Carbon Nanomaterials

Background:

• Electrochemical conversion of carbon dioxide (CO2) to formate is crucial but hindered by challenges with tin (Sn)-based catalysts, including poor conductivity and structural instability.
• Existing Sn catalysts struggle with efficient formate production at industrially relevant current densities due to limitations in charge transport and intermediate binding.
• Developing durable and highly efficient catalysts is essential for advancing CO2 utilization technologies.

Purpose of the Study:

• To engineer a novel catalyst for efficient and durable electrochemical CO2 conversion to formate.
• To address limitations of Sn-based catalysts by employing nanogrid-directed interfacial electric field engineering.
• To enhance charge transport, optimize reaction kinetics, and improve catalyst stability.

Main Methods:

• Fabrication of a Sn@CNT catalyst by confining Sn nanoparticles within a conductive carbon nanotube nanogrid framework.
• Utilizing operando spectroscopy and theoretical simulations to investigate the catalyst's performance and reaction mechanisms.
• Testing the catalyst in flow and solid-electrolyte cells under alkaline conditions to assess formate and formic acid production efficiency and durability.

Main Results:

• The Sn@CNT catalyst achieved a Faradaic efficiency (FE) of 95.6% for formate at 300 mA cm⁻².
• The catalyst maintained over 90% FE for 200 hours in a flow cell and enabled stable production of 1.1 M formic acid for over 300 hours in a solid-electrolyte cell.
• Interfacial electric field engineering optimized H2O dissociation, *HCOOH intermediate kinetics, and suppressed the hydrogen evolution reaction.

Conclusions:

• Nanogrid-directed interfacial electric field engineering is a broadly applicable strategy for designing efficient and stable electrochemical interfaces.
• The Sn@CNT catalyst offers a promising solution for industrial-scale CO2-to-formate electrosynthesis.
• This approach provides design principles for advanced catalysts in CO2 reduction and other electrochemical applications.