Carbon capture and utilization (CCU) technologies are playing a growing role in efforts to address climate change by trapping carbon dioxide emissions and converting them into useful fuels or chemicals. However, for these systems to be commercially viable, they must run continuously for thousands of hours—a goal that has been hampered by persistent technical issues like salt buildup inside electrochemical reactors.
Researchers at Rice University have discovered a surprisingly straightforward solution to one of the most critical bottlenecks in CO₂ electroreduction systems. Instead of using water to humidify carbon dioxide gas before it enters the reactor, the team bubbled the gas through a mild acid solution. This small change allowed the system to remain stable for over 4,500 hours—more than 50 times longer than standard water-based setups.
The main issue in traditional systems is the formation of potassium bicarbonate, a poorly soluble salt. Potassium ions in the electrolyte react with carbon dioxide and form this salt, which then accumulates inside the reactor. It clogs gas channels, blocks CO₂ access to catalysts, and floods electrodes—causing devices to fail in a matter of hundreds of hours.
The Rice team replaced the conventional water-based humidification with acid vapors from solutions such as hydrochloric, formic, or acetic acid. These vapors subtly altered the chemistry in the system, preventing potassium bicarbonate from crystallizing. Instead, the salt stayed dissolved and was carried away by the gas flow, keeping the system free from blockages.
The researchers tested the approach with a silver-based catalyst in a lab-scale setup and achieved more than 2,000 hours of stable operation. In a larger system with a 100-square-centimeter electrolyzer, the setup ran for over 4,500 hours without major degradation. In contrast, systems using water humidification typically failed after just 80 hours.
The acid vapor technique also worked across a range of catalysts—including zinc oxide, copper oxide, and bismuth oxide—highlighting its versatility for different CO₂ conversion targets. Importantly, the use of mild acid concentrations meant that key components such as membranes and electrodes were not damaged or corroded.
To better understand the mechanism, the team built transparent reactors to directly observe salt formation. In water-based systems, salt crystals began forming within 48 hours. In acid-treated systems, no accumulation was observed even after hundreds of hours.
This acid vapor method offers a rare combination of simplicity, durability, and scalability. Because it requires only minor modifications to existing humidification systems, the solution can be implemented in industrial-scale devices without the need for expensive redesigns.
By solving a long-standing durability issue with a low-tech fix, the Rice team has taken a significant step toward making carbon capture and utilization technologies more commercially viable, cost-effective, and sustainable.
By Impact Lab
