[Reading Science]219% Efficiency? 'Domino Reaction' Produces Two Hydrogen Peroxide Molecules from a Single Photon

KIST Breaks Through Conventional Photochemical Efficiency Limits with Chain Reaction

Produces 1% Concentration at 4–8W Low Power…Potential for On-Site Water Treatment Production

A new technology has been developed that more than doubles the efficiency of producing hydrogen peroxide (H₂O₂) using light, surpassing previous limitations. Unlike the traditional approach where a single photon only triggers one reaction, the key innovation here is the use of a "chain reaction," in which the initial reaction leads to a series of subsequent reactions.

The Korea Institute of Science and Technology (KIST) announced on September 9 that the research team led by Jihye Byun and Jaesik Jeong at the Climate and Environment Research Center succeeded in producing more than two hydrogen peroxide molecules per photon using this method. The photon utilization efficiency reached as high as 219.1%.

Optimization process for hydrogen peroxide production using light. After 5,888 experiments and AI analysis, the optimal reaction solution was found, and verification was conducted for liter-scale production and actual water treatment application. Provided by the research team

Hydrogen peroxide is widely used not only as a disinfectant but also in water purification, wastewater treatment, and semiconductor cleaning. Currently, more than 95% of global production is carried out in large chemical plants. Because of this, high-concentration hydrogen peroxide must be transported and stored at the point of use, resulting in significant costs and safety risks.

Consequently, research has been ongoing to develop technology for producing hydrogen peroxide on-site using light. The main challenge has been efficiency. With conventional photocatalyst methods, each photon transfers energy to a catalyst and causes one reaction, meaning the theoretical efficiency limit has been considered essentially as one hydrogen peroxide molecule per photon, or 100%.

One Photon Topples the Dominoes of Reaction

The research team overcame this limitation using a "chain reaction." When a photon initiates the first reaction, the resulting substance triggers the next reaction, which then leads to additional reactions. While a single photon is not directly used multiple times, the chain of reactions set off by one photon ultimately yields multiple hydrogen peroxide molecules.

To find the optimal combination of substances for absorbing light, supplying hydrogen, and acting as the solvent, the research team conducted a total of 5,888 experiments across 184 different combinations. Artificial intelligence (AI) was then used to pinpoint the best reaction conditions.

As a result, photon utilization efficiency reached 219.1%. This 219.1% does not mean that an input of 100 units of energy produced 219 units. Instead, it signifies that, on average, more than two hydrogen peroxide molecules were produced for every photon that triggered a chain reaction.

This high figure was not limited to small-scale laboratory experiments. The team successfully produced high-purity hydrogen peroxide at a concentration of 1%—a level used in industrial applications—in a 1-liter scale reactor. When this product was applied to water treatment, it removed more than 99.95% of the endocrine-disrupting compound bisphenol-A.

On-site Production Using Power Comparable to a Smartphone Charger

Another notable feature is the required power. Unlike previous solar catalyst studies that used light sources rated at about 300W, this new technology operates at just 4 to 8 watts—roughly the power level of a smartphone charger.

Research team photo. From left: Hyekyung Cho, Postdoctoral Researcher at KIST (currently at the Agency for Defense Development, first author), Jihye Byun and Jaesik Jeong, Principal Researchers at KIST (corresponding authors). Provided by KIST

If scaled up and commercialized, this technology could enable "distributed production" in which hydrogen peroxide needed at water purification or sewage treatment facilities is produced and used on-site. This could significantly reduce the need to transport and store high-concentration hydrogen peroxide from large-scale plants.

Jihye Byun, a KIST researcher, stated, "By enabling a continuously linked reaction triggered by a single instance of light, we have surpassed the efficiency limits of conventional photochemical hydrogen peroxide production. This technology could be advanced to produce hydrogen peroxide directly wherever it is needed—including at water and wastewater treatment plants, smart farms, advanced industrial sites, or even emergency water treatment in disaster areas."

The research findings have been published online in the latest issue of the international journal "Joule."

This content was produced with the assistance of AI translation services.