Researchers at Ulm University and Friedrich-Schiller-Universität Jena have built a molecular system that captures solar energy in a water-soluble redox copolymer, stores it at more than 80% charging efficiency for several days, and releases it as hydrogen with 72% conversion efficiency whenever required.
Image: Elvira Eberhardt, Ulm University
From pv magazine España
A research team from Ulm University and Friedrich Schiller University Jena has developed a molecular solar battery that stores photovoltaic energy and releases it as hydrogen on demand – including in the dark, without any solar input. The results were published in Nature Communications.
The system’s core is a water-soluble copolymer with high redox activity, designed to act simultaneously as an electron storage medium and a photocatalytic platform. The material captures electrons generated by solar irradiation and holds them stably for several days at a charging efficiency of more than 80%.
The approach decouples solar generation from hydrogen production – a departure from conventional systems that require electrolysis and renewable generation to run simultaneously. Once energy is stored in the copolymer, adding an acid and a hydrogen evolution catalyst combines the stored electrons with protons, generating hydrogen at 72% conversion efficiency. The process works in darkness, giving operators flexibility over when and how hydrogen is produced.
The system is also chemically reversible. Multiple charge, storage, and discharge cycles are possible without isolating the active material. Regeneration requires only a pH adjustment – neutralization – which reactivates the photocatalytic process under irradiation. The researchers said the cyclical behavior, grounded in reversible copolymer redox reactions, positions the material as a candidate for chemical energy storage applications.
The work brings together macromolecular chemistry and photocatalysis – two fields with limited prior overlap – in a single molecular architecture that handles capture, storage, and conversion. The researchers said the approach could support low-cost, scalable hydrogen storage, with potential applications in energy-intensive industrial processes such as steelmaking and synthetic fuel production, where on-demand hydrogen generation could ease the integration of variable renewables.
The research is part of the CataLight consortium, which focuses on converting solar energy into chemical energy using molecular catalysts.
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.
More articles from Pilar Sánchez Molina
Please be mindful of our community standards.
Your email address will not be published. Required fields are marked *
Comment *
Name *
Email *
Website
Save my name, email, and website in this browser for the next time I comment.


Δ
By submitting this form you agree to pv magazine using your data for the purposes of publishing your comment.
Your personal data will only be disclosed or otherwise transmitted to third parties for the purposes of spam filtering or if this is necessary for technical maintenance of the website. Any other transfer to third parties will not take place unless this is justified on the basis of applicable data protection regulations or if pv magazine is legally obliged to do so.
You may revoke this consent at any time with effect for the future, in which case your personal data will be deleted immediately. Otherwise, your data will be deleted if pv magazine has processed your request or the purpose of data storage is fulfilled.
Further information on data privacy can be found in our Data Protection Policy.
Legal Notice Terms and Conditions Data Privacy © pv magazine 2026
Δ
This website uses cookies to anonymously count visitor numbers. View our privacy policy. ×
The cookie settings on this website are set to “allow cookies” to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click “Accept” below then you are consenting to this.
Close

source