Photochemical hydrogen generation


June 7, 2022

Image titel:


Photochemical hydrogen generation

In this photoreactor, the research team succeeded in storing light energy in their newly developed molecule, © Heiko Grandel

Photoreactor – storing light energy in developed molecule, © Heiko Grandel

Instead of by electrolysis, hydrogen can also be produced photochemically. A research team at Universität Ulm has developed a molecule that stores energy from light by holding onto electrons released by another molecule. The hydrogen can then be produced with this stored energy at a later time as needed.

The new molecule is a type of covalent photosensitizer–polyoxometalate (PS-POM) dyad. Dyad means that the compound fulfills two functions: one part of the molecule is responsible for the transfer of electrons and another part stores the energy. The exact name of the molecule does not appear in the publication. “The name would be about four lines long,” explained Dr. Sven Rau of the Institut für Anorganische Chemie der Universität Ulm (institute for inorganic chemistry at the university Universität Ulm).


The substance is liquid at ambient conditions, which makes storage easier. If you bring it together with a substance that emits electrons when exposed to light, each storage molecule takes up two electrons. If the substance is stored in the dark and in the absence of air, the molecules retain the electrons and don’t release them until positive hydrogen ions (H+) are added. This can be done for example with an acid. In the experiment, the researchers used sulfuric acid.

The hydrogen ions react with the stored electrons to form hydrogen. The reaction of the storage molecule is reversible. This means that it can be charged and discharged with electrons again and again. The research team was not only the first to show how the hydrogen can be produced with the help of light, they could also control the timing of this reaction in such a way that it can be used for energy storage.

The next steps entail some optimization work. For example, the efficiency so far is still very low. “We have shown that it works. Now we, and all other scientists, can increase the efficiency,” said Rau. “In addition, a number of the loaded molecules react prematurely, and according to a yet completely unknown mechanism,” he said. In the first experiments, one sixth of the stored electrons were lost within 150 minutes. However, Rau thinks storage for days or weeks is possible, “in principle also longer.”

The to-do list also includes the search for a suitable reactor design as well as for sustainable and cost-effective reagents. For example, instead of the nitrogen compound now used, an alcohol could be used as an electron donor. Or in the far future, even water, which could directly supply the H+ ions.

Although this temporary energy storage technique is unique, researchers from Ulm are not the only ones looking for a photoelectric route to hydrogen. The Helmholtz-Zentrum Geesthacht, for example, is working on an artificial leaf. What all methods have in common, however, is that they are still in the laboratory stage.

Author: Eva Augsten

Here are interesting and current articles on the topic of hydrogen – stocks and the stock market!

Economic prospects for companies in the hydrogen sector | Future, stocks & hydrogen companies on the stock exchange and more…

Which hydrogen companies will prevail in the competitive market in the long term? Get tips and cartwheels and learn more about risks or opportunities. Our stock market specialist and expert author Sven Jösting reports critically, independently and competently.

Jun 13 2024

H2 Bank Selects Seven Projects”

The European Commission is allocating nearly 720 million euros to seven projects for renewable...
Jun 13 2024

World’s one-of-a-kind H2 test lab

Electrolyzers on the test bench In Hydrogen Lab Bremerhaven, manufacturers and operators of...
Jun 13 2024

First commercial green hydrogen production

Solar Global operates electrolyzer plant in Czech Republic An electrolyzer in the town of...
Jun 12 2024

Hydrogen 3.0

“Are we on the cusp of a hydrogen revolution or merely witnessing the build-up of another bubble?”...
Jun 12 2024

Mechatronic H2 pressure regulator

Up until now, Italian company Landi Renzo has been mainly known for its conversion sets for gas...
Jun 11 2024

Establishment of a metrological infrastructure

Flow measurement of high-pressure gas and liquid hydrogen In the field of flow measurement, the...
Jun 11 2024

FRHY Stack, first of its kind!

Technology platform for high-rate electrolyzer production The cooperative FRHY project, which...
Jun 10 2024

HySupply – German-Australian hydrogen bridge

Acatech and BDI show what’s feasible Defossilizing the energy system is an important goal of the...
Jun 05 2024

In the beginning was the refueling station

Creating planning security through the development of H2 infrastructure We have long discussed the...
Jun 04 2024

Digital potential

Low-cost green hydrogen through digitalization Plans to expand Germany’s hydrogen landscape are...
Jun 04 2024

A new energy infrastructure is emerging

“Green” and “blue” ammonia from other continents to come to Europe Ammonia produced from...
May 31 2024

Fuel cell systems for grid hardening

Interview with Christian Leu and Benedikt Eska from Axiosus An important but often neglected area...
May 30 2024

A new energy infrastructure is emerging

“Green” and “blue” ammonia from other continents to come to Europe Ammonia produced from...
May 16 2024

New CFO for H-Tec Systems

Electrolyzer manufacturer H-Tec Systems underwent restructuring at the turn of the year and...
May 16 2024

One-man show continues to grow

Hydrogeit Verlag celebrates its 20th anniversary The Hydrogeit Verlag publishing house has been...
May 15 2024

Hydrogen for the post-coal era

Nuclear energy also to power electrolysis in Hungary In May 2021, Hungary published its national...
May 15 2024

Hüwener to lead OGE

Thomas Hüwener will become the new management spokesman for transmission system operator OGE from...
May 15 2024

Accelerating expansion and reducing hurdles

German government adopts power plant strategy It took a long time, but now it's here – the power...
May 15 2024

Brussels approves IPCEI projects

3rd funding wave for H2 infrastructure measures The decision has finally come. In mid-February...
May 15 2024

Apex becomes H2APEX

Apex, headquartered in Rostock, Germany, is continuing to make big strides forward in the hydrogen...


Leave a Reply