A photoelectrochemical device uses sunlight, water, and oxygen to produce hydrogen peroxide efficiently, stably, and at scalable rates without grid electricity.
(Nanowerk Spotlight) Hydrogen peroxide is a simple molecule with outsized importance. It disinfects drinking water, sterilizes medical equipment, and powers chemical synthesis. Yet nearly all of it is made through the anthraquinone process, an energy-heavy industrial method that depends on fossil fuels, organic solvents, and centralized plants. This creates cost, environmental impact, and logistical constraints, especially for regions that need smaller, local supplies.
Researchers seeking cleaner alternatives, have been exploring both electrochemical and photoelectrochemical approaches that could make hydrogen peroxide on-site from only water, oxygen, and renewable energy. Many designs have shown promise in the lab but have stumbled on the same obstacles. Some require an external electrical bias, meaning they need an extra voltage from a power source to push the reactions forward. This added electrical input increases complexity, raises energy demands, and limits the ability to run purely on sunlight. Others rely on expensive precious metal catalysts that raise costs and create supply vulnerabilities. Many lose performance over time, with catalysts degrading under illumination or shifting to unwanted reaction pathways. Scaling these systems often causes sharp drops in efficiency, limiting their practical impact.
Scientists in China addressed these problems by delivering a photoelectrochemical system that works without any bias at all. It runs solely on sunlight and is built entirely from earth-abundant materials. The device produces hydrogen peroxide directly from water and oxygen with high efficiency, combining material choice, catalyst design, and cell architecture to meet three goals simultaneously: high efficiency, long-term stability, and scalability.
Schematic illustration of the fabrication process. (Image: Reprinted with permission by Wiley-VCH Verlag)
At its core, the system combines a bismuth vanadate (BiVO₄) photoanode with a carbon-based cathode in a single circuit. The photoanode absorbs visible light to oxidize water into oxygen gas, while the cathode reduces oxygen into hydrogen peroxide. The energy levels of both electrodes are matched so that light alone drives both reactions without the need for that extra electrical push. This direct coupling simplifies the system and enables operation in off-grid environments.
Bismuth vanadate was selected for its light absorption range, chemical durability, and abundance. To increase water oxidation speed, its surface was coated with cobalt phosphate, a co-catalyst that promotes faster electron transfer. The cathode is made from carbon black with oxygen-containing functional groups. These groups favor the two-electron oxygen reduction pathway, which produces hydrogen peroxide instead of fully reducing oxygen to water via the four-electron pathway. Suppressing this competing reaction is critical because it ensures nearly all electrons contribute to the target product, maximizing efficiency.
The device operates in an aqueous electrolyte under ambient temperature and pressure. When exposed to simulated sunlight, it achieved a solar-to-chemical conversion efficiency of over 1 percent without any bias—comparable to or better than many biased systems. Hydrogen peroxide concentration steadily increased during continuous operation, reaching practical-use levels with no measurable drop in rate. Stability tests showed that the electrodes retained both structure and activity over many hours of illumination, demonstrating resilience under operating conditions that often degrade conventional catalysts.
Scalability was assessed by enlarging the electrodes and increasing the electrolyte volume. The system maintained high performance, and its modular design allows multiple units to be linked for higher output. Production rates scaled proportionally with electrode area, suggesting that industrially relevant outputs are achievable without major redesign. This makes the technology a candidate for decentralized hydrogen peroxide production in rural water treatment facilities, field hospitals, and remote industrial operations.
Mechanistic studies confirmed the operation of the desired reaction pathways. At the photoanode, light-generated holes oxidized water to oxygen, which was then reduced at the cathode by electrons to form hydrogen peroxide. Control experiments verified that hydrogen evolution and four-electron oxygen reduction were effectively suppressed, and that catalyst composition and electrolyte chemistry were essential for maintaining selectivity.
By combining earth-abundant materials, bias-free operation, and scalable architecture, this work offers a practical route to sustainable hydrogen peroxide production. The system eliminates dependence on grid electricity and expensive metals, avoids the waste of the anthraquinone process, and delivers stable performance under sunlight. More broadly, it illustrates how targeted materials engineering and device design can bring solar-driven chemical manufacturing closer to real-world deployment.
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Hangxun Xu (University of Science and Technology of China)
, 0000-0003-1645-9003 corresponding author
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