new findings

Rice research team's study keeps CO2-to-fuel devices running 50 times longer

Ahmad Elgazzar, Haotian Wang and Shaoyun Hao were members of a Rice University team that recently published findings on how acid bubbling can improve CO2 reduction systems. Photo courtesy Rice.

In a new study published in the journal Science, a team of Rice University researchers shared findings on how acid bubbles can improve the stability of electrochemical devices that convert carbon dioxide into useful fuels and chemicals.

The team led by Rice associate professor Hoatian Wang addressed an issue in the performance and stability of CO2 reduction systems. The gas flow channels in the systems often clog due to salt buildup, reducing efficiency and causing the devices to fail prematurely after about 80 hours of operation.

“Salt precipitation blocks CO2 transport and floods the gas diffusion electrode, which leads to performance failure,” Wang said in a news release. “This typically happens within a few hundred hours, which is far from commercial viability.”

By using an acid-humidified CO2 technique, the team was able to extend the operational life of a CO2 reduction system more than 50-fold, demonstrating more than 4,500 hours of stable operation in a scaled-up reactor.

The Rice team made a simple swap with a significant impact. Instead of using water to humidify the CO2 gas input into the reactor, the team bubbled the gas through an acid solution such as hydrochloric, formic or acetic acid. This process made more soluble salt formations that did not crystallize or block the channels.

The process has major implications for an emerging green technology known as electrochemical CO2 reduction, or CO2RR, that transforms climate-warming CO2 into products like carbon monoxide, ethylene, or alcohols. The products can be further refined into fuels or feedstocks.

“Using the traditional method of water-humidified CO2 could lead to salt formation in the cathode gas flow channels,” Shaoyun Hao, postdoctoral research associate in chemical and biomolecular engineering at Rice and co-first author, explained in the news release. “We hypothesized — and confirmed — that acid vapor could dissolve the salt and convert the low solubility KHCO3 into salt with higher solubility, thus shifting the solubility balance just enough to avoid clogging without affecting catalyst performance.”

The Rice team believes the work can lead to more scalable CO2 electrolyzers, which is vital if the technology is to be deployed at industrial scales as part of carbon capture and utilization strategies. Since the approach itself is relatively simple, it could lead to a more cost-effective and efficient solution. It also worked well with multiple catalyst types, including zinc oxide, copper oxide and bismuth oxide, which are allo used to target different CO2RR products.

“Our method addresses a long-standing obstacle with a low-cost, easily implementable solution,” Ahmad Elgazzar, co-first author and graduate student in chemical and biomolecular engineering at Rice, added in the release. “It’s a step toward making carbon utilization technologies more commercially viable and more sustainable.”

A team led by Wang and in collaboration with researchers from the University of Houston also shared findings on salt precipitation buildup and CO2RR in a recent edition of the journal Nature Energy. Read more here.

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A View From HETI

Texas ranked in the bottom half on WalletHub's list of the most energy-efficient states. Photo via unsplash.

Texas has room to improve when it comes to energy efficiency, recent data from WalletHub shows.

The personal finance website ranked Texas at No. 35 on the latest Most & Least Energy-Efficient States list. Texas improved by one spot on the 2025 report, after coming in at No. 36 last year.

The report measured and ranked the efficiency of auto energy and home energy consumption in the 48 U.S. mainland states based on data from the U.S. Census Bureau, National Climatic Data Center, U.S. Energy Information Administration and the U.S. Department of Transportation – Federal Highway Administration.

Texas earned an overall score of 50.60. It was ranked No. 27 for home energy efficiency and No. 41 for auto efficiency. By comparison, No. 1-ranked Vermont earned a score of 85.30, ranking No. 2 for home energy and No. 6 for out energy.

The top five overall states included:

  • No. 1 Vermont
  • No. 2 California
  • No. 3 Washington
  • No. 4 New York
  • No. 5 Massachusetts

South Dakota earned the top rank for home energy efficiency, and Massachusetts earned the top rank for energy efficiency.

“Energy efficiency doesn’t just help save the planet – it also helps save you money by lowering the amount of electricity, gas, oil or other types of energy you need to consume. While there are some steps you can take to become more energy-efficient on your own, living in the right area can give you a big boost," WalletHub analyst Chip Lupo said in the report. "For example, certain states have much better public transportation systems that minimize your need to drive, at least in big cities. Some places also have better-constructed buildings that retain heat better during the winter or stay cooler during the summer.”

According to the report, some progress is being made in increasing energy efficiency across the country. The U.S. Energy Information Administration expects 26 percent of electricity generation in 2026 will come from renewables. A number of them are being developed in the Houston area, including recent announcements like the Pleasure Island Power Collective in Port Arthur.

Still, Houston earned an abysmal ranking on WalletHub's greenest cities in the U.S. report earlier this year, coming in at No. 99 out of 100. Read more here.

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