[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 technology that uses light to more than double the efficiency of hydrogen peroxide (H₂O₂) production for the first time, compared to conventional limits, has been developed. The key breakthrough lies in utilizing a "chain reaction"—unlike traditional methods, where each photon of light induces a single reaction, in this approach, the initial reaction continuously triggers subsequent reactions.

The Korea Institute of Science and Technology (KIST) announced on September 9 that the research team led by Dr. Jihye Byun and Dr. Jaesik Jung at the Climate and Environment Research Center has succeeded in producing more than two molecules of hydrogen peroxide per photon using this method. The photon utilization efficiency reached 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 for disinfection but also in water and wastewater treatment and semiconductor cleaning. Currently, more than 95% of global production takes place at large chemical plants. Transporting and storing highly concentrated hydrogen peroxide to required sites incurs substantial costs and safety concerns.

As a result, there has been ongoing research into technologies that allow hydrogen peroxide to be produced directly where needed using light. However, the challenge has been efficiency. In conventional photocatalytic methods, each photon delivers energy to a catalyst to induce a single reaction, essentially limiting hydrogen peroxide production to one molecule per photon, with 100% widely considered the upper efficiency threshold.

A Single Photon Sparks a 'Domino' of Reactions

The research team overcame this limitation with a "chain reaction." When a photon triggers the first reaction, the resulting molecule induces the next reaction, which in turn leads to further reactions. Although a single photon is not used multiple times directly, the reaction it sparks continues in a chain, ultimately yielding several hydrogen peroxide molecules.

To identify the optimal combination of light-absorbing materials, hydrogen donors, and reaction solvents, the team conducted a total of 5,888 experiments across 184 combinations. Artificial intelligence (AI) was then harnessed to pinpoint the ideal reaction conditions.

As a result, photon utilization efficiency reached 219.1%. Here, 219.1% does not mean obtaining 219 units for every 100 units of energy input. Rather, it indicates that, on average, more than two molecules of hydrogen peroxide were produced per photon, thanks to the chain reaction initiated by a single photon.

The achievement went beyond recording impressive numbers in the laboratory. The team achieved stable production of high-purity hydrogen peroxide at 1% concentration—a level used in industrial settings—using a 1-liter scale reactor. When applied to water treatment, more than 99.95% of the environmental hormone substance bisphenol A was removed.

On-Site Production Using the Power of a Smartphone Charger

Another noteworthy feature is the required power. While traditional solar photocatalyst research uses light sources in the 300-watt range, this new technology operates at just 4–8 watts—comparable to the power required for 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 the technology scales up to commercialization, "distributed production" of hydrogen peroxide on-site—such as in water purification or sewage treatment plants—could become feasible. This would significantly reduce the burdens of transporting and storing high-concentration hydrogen peroxide produced at centralized plants.

Dr. Jihye Byun of KIST stated, "By enabling a single light-initiated reaction to continue in sequence, we have surpassed the traditional efficiency limits of photochemical hydrogen peroxide production. This technology can be developed further to enable on-site hydrogen peroxide generation where needed—at water purification plants, sewage treatment centers, smart farms, advanced industrial sites, and in emergency water treatment during disasters."

The results of this study were published online in the latest issue of the international journal, "Joule."

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