Microenvironment Tuning through Bi Morphology for Efficient Bicarbonate Electroreduction.

Area of Science:

• Electrochemistry
• Catalysis
• Carbon dioxide conversion

Background:

• Bicarbonate electroreduction is a promising CO2 conversion pathway.
• Current methods face limitations in CO2 concentration and interfacial pH control.
• Optimizing these factors is crucial for efficient formate production.

Purpose of the Study:

• To design a catalyst that enhances mass transfer and regulates interfacial pH for bicarbonate electroreduction.
• To investigate the effect of interfacial pH on CO2 generation and formate selectivity.
• To improve the overall performance of cation exchange membrane-based CO2 conversion systems.

Main Methods:

• Fabrication of bismuth nanoflower (Bi-NF) catalysts with interconnected channels.
• Electrochemical open-circuit potential measurements to quantify interfacial pH.
• Integration of hydrophilic filter membranes to optimize ion and gas transport.
• Performance evaluation of the optimized electrode system under varying current densities.

Main Results:

• The Bi-NF catalyst effectively enhances CO2 diffusion and regulates local pH.
• Elevated interfacial pH promotes in situ CO2 generation, boosting selectivity.
• Optimized system achieved nearly 100% Faradaic efficiency for formate at 50 mA cm-2.
• A practical partial current density of 240 mA cm-2 was achieved at 3.5 V.

Conclusions:

• Morphology engineering of catalysts, like Bi-NF, is key to improving bicarbonate electroreduction.
• Controlled mass transport and interfacial pH management are critical for high-performance CO2 conversion.
• This work provides insights into the mechanisms governing bicarbonate electrolysis and offers a strategy for enhanced performance.