Newswise — From brightly colored textile dyes to persistent pesticides and antibiotics, many modern pollutants dissolved in water — such as Bisphenol A — resist traditional treatment methods. A promising approach uses electricity to power chemical reactions in water over an electrode surface. Much like in a battery, electrodes send and receive electrical current that drives chemical reactions.

This process, known as electrocatalysis, generates a class of highly reactive oxygen-containing compounds, known as reactive oxygen species or oxidants, at the electrode surface. These powerful oxidants, which include ozone and hydrogen peroxide, can break down even the most stubborn contaminants, producing cleaner water. However, because these oxygen species are unstable, degrade over time and exist in trace amounts — down to the parts-per-billion level — they have been notoriously difficult to detect and quantify.

In a study published in ACS Catalysis, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory report a new method for detecting and quantifying these short-lived oxygen species in real time with unprecedented sensitivity. Their approach revealed not only how much of each oxidant is produced, but also which specific species are formed under different treatment conditions.

“These oxygen species don’t last long, and they’re hard to detect individually,” said Argonne Electrochemist Scientist Pietro Papa Lopes, who led the study. ​“But knowing which ones are present and in what quantities is essential for improving water treatment technologies.”

Importantly, the team’s findings have applications beyond water treatment. One example is fuel cells. They convert hydrogen or other chemical fuels into electricity. Another is electrolyzers. They can split water molecules to produce hydrogen fuel or convert carbon dioxide into aviation fuels, for example.

The researchers used a method involving two electrodes to determine which oxidants were generated at the electrode surface. The first was a disk where a water oxidation reaction took place, generating the reactive oxygen species. The second was a concentric ring electrode. It produced an electrical signal that could detect and quantify the reactive oxygen species.

They tested the performance of three materials as the disk electrode: lead dioxide, platinum and iridium oxide. Lead dioxide was selected for its known ability to generate significant amounts of ozone and relevance to pollutant degradation. Platinum and iridium oxide were included as controls, as earlier studies had suggested they do not produce measurable amounts of reactive oxygen species. But the results told a different story.

“Somewhat to our surprise, at high voltages, all three electrode materials produced measurable levels of hydrogen peroxide and ozone,” said Papa Lopes. ​“That finding matters. Those oxidants can degrade membranes and other components used in electrochemical technologies, which could impact their long-term performance.”

Another key result involved Faradaic efficiency — a measure of how much input electricity is converted into useful chemical products. The team found that lead dioxide converted up to 30% of the electrical energy into ozone. That’s a high efficiency for systems of this type and suggests strong potential for scalable pollutant breakdown technologies.

The study provides a new benchmark for scientists and engineers working to advance electrochemical water purification. By establishing a consistent, sensitive method for identifying and quantifying reactive oxygen species in electrochemical systems, the research enables better system design and more meaningful comparisons across experiments and technologies.

This work was conducted through the Advanced Materials for Energy-Water Systems (AMEWS) Center, an Energy Frontier Research Center led by Argonne and supported by DOE. AMEWS seeks to understand how water — and the substances it carries — interacts with solid materials at the molecular level.

In addition to Papa Lopes, contributing authors at Argonne include Igor Messias, Jacob Kupferberg, Askley Bielinski and Alex Martinson, as well as Raphael Nagao at the Universidade Estadual de Campinas in Brazil. The research was funded by the DOE Office of Basic Energy Sciences.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology by conducting leading-edge basic and applied research in virtually every scientific discipline. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.