Sequentially Regulating Potential-Determining Step for Lowering CO₂ Electroreduction Overpotential over Te-Doped Bi...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic conversion of carbon dioxide (CO2) to formate is a key strategy for CO2 utilization.
• High overpotentials and energy barriers in proton-coupled electron transfer (PCET) processes limit selectivity and efficiency.
• Understanding and controlling the potential-determining step (PDS) is crucial for optimizing CO2 electroreduction.

Purpose of the Study:

• To develop an efficient electrocatalyst for CO2 to formate conversion with high selectivity at low overpotentials.
• To investigate the role of Te doping and nanostructure morphology in regulating the electrocatalytic mechanism.
• To demonstrate the practical applicability of the developed catalyst in a membrane electrode assembly (MEA) device.

Main Methods:

• Computational studies (e.g., DFT) to analyze reaction mechanisms and energy barriers.
• Synthesis of Te-doped Bi (TeBi) nanotips with controlled Te content.
• Electrochemical characterization including cyclic voltammetry and chronoamperometry.
• Performance evaluation in a membrane electrode assembly (MEA) device.

Main Results:

• Te doping shifted the PDS and lowered activation barriers for key intermediates (*OCHO and *HCOOH).
• TeBi nanotips achieved >90% Faradaic efficiency for formate production within a wide potential window (-0.57 V to -1.08 V).
• The catalyst exhibited robust stability due to strong Bi-Te covalent bonds.
• An optimized MEA device demonstrated a formate production rate of 10.1 mmol h⁻¹ cm⁻² at 3.2 V.

Conclusions:

• Sequential regulation of the PDS through Te doping and nanostructure engineering is effective for enhancing CO2 electroreduction.
• TeBi nanotips offer a promising pathway for efficient and selective formate production.
• The high performance and stability suggest significant potential for industrial CO2 upgrading applications.