Water Management Using Massively Produced Calcium Carbonate for Pilot-Scale CO₂ Electrolysis.

Area of Science:

• Electrocatalysis
• Materials Science
• Chemical Engineering

Background:

• Scalable, catholyte-free membrane electrode assemblies (MEAs) face performance limitations due to inadequate interfacial water and proton supply.
• Developing efficient proton-feeding microenvironments is crucial for advancing MEA technology.

Purpose of the Study:

• To present a general strategy for creating an ideal proton-feeding microenvironment using calcium carbonate (CaCO3).
• To investigate the role of CaCO3 in stabilizing interfacial water and facilitating proton transport.
• To demonstrate the effectiveness of CaCO3-based catalysts for industrial electrocatalysis.

Main Methods:

• In situ spectroscopy and theoretical simulations to analyze CaCO3 surface properties and water interactions.
• Synthesis of metal-loaded CaCO3 (M/CaCO3) catalysts (M = Zn, Cu).
• Electrochemical testing of catalysts in a 100 cm2 electrolyzer stack for CO2 conversion and syngas production.

Main Results:

• CaCO3's hydrophilic surface selectively enriches and stabilizes reactive liquid-like water molecules, creating an efficient proton highway.
• Metal-loaded CaCO3 catalysts exhibit exceptional performance at industrial-relevant current densities.
• Catalysts synthesized from unpurified cement plant flue gas enable high-rate CO2 conversion to C2+ (77.97% Faradaic efficiency) or syngas (19 L h-1).

Conclusions:

• Calcium carbonate provides an effective strategy for manipulating interfacial water dynamics in electrocatalysis.
• This approach enables the development of high-performance, scalable catalysts from abundant natural minerals.
• The findings establish a new paradigm for industrial electrocatalysis using earth-abundant materials.