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Energy can be harnessed from many sources. Among them, renewable sources have increasingly moved into the spotlight of governments and energy producers, as they are beneficial to the climate as well as life on the planet. One such green source is hydrogen. It is abundant and environmentally-friendly as it can be extracted from water with the help of renewable sources. Also, producing energy and fuels from hydrogen would also help move away from fossil fuels as energy source, which are among the main culprits of climate change.

Hydrogen, however, can not only be used for energy production. It is also an important chemical for many industrial processes, most notably in steel making and ammonia production. Using clean hydrogen in these industries would therefore also be a valuable contribution to making the human footprint on earth more sustainable.

Now (2023), a multi-institutional team led by Argonne National Laboratory has developed a low-cost catalyst for a process which can produce clean hydrogen from water. The other contributors involved in the project include DOE’s Sandia National Laboratories and Lawrence Berkeley National Laboratory, as well as Giner Inc.

The team of scientists used Proton exchange membrane (PEM) electrolysers, a new technology for this process, in order to receive clean hydrogen. Proton exchange membrane (PEM) electrolysers can split water into hydrogen and oxygen with higher efficiency at near room temperature. This advantage, i.e. the reduced energy demand, makes them an ideal choice for producing clean hydrogen by using renewable but intermittent sources, such as solar and wind.

This electrolyser works with separate catalysts for each of its electrodes (cathode and anode). This causes the cathode catalyst to yield hydrogen, while the anode catalyst forms oxygen. The main problem with PEMs, however, is that the anode catalyst uses iridium, which is quite an expensive material and in short supply. This lack of supply and high cost of iridium pose a major obstacle to widespread adoption of electrolysers of this kind.

The scientists tried to overcome this problem by using cobalt as the main ingredient in the new catalyst which is much cheaper than iridium. ​Using the cobalt-based catalyst helped them remove the main bottleneck of cost to producing clean hydrogen in an electrolyser. Giner Inc., a research and development company in the field of electrolyzers and fuel cells, evaluated the new catalyst using its PEM electrolyser test stations under industrial operating conditions. They found that the performance and durability far exceeded that of competitors’ catalysts.

Scientists have long tried to find a method to produce clean fuel from hydrogen using electrolysers. In 2013, a team of scientists sought to optimise the production of hydrogen from waste water using electrolysis in laboratory or over the sun. The additive they used was NaCl. They analysed produced hydrogen flow criteria, electrolysis efficiency and electric power consumption. The most significant outcome of the experiment was the significant increase in the produced hydrogen flow by the addition of the additive. They also found that gas liquor and urine yielded better results compared to the others tested electrolytes. The addition of NaCl in the electrolytes was found to activate the electrochemical reactions and produced more hydrogen. 

Image: Photographs of the photovoltaic model and the electrolysers with their corroded electrodes



Source: Romdhane ben slama/ Production of Hydrogen by Electrolysis of Water: Effects of the Electrolyte Type on the Electrolysis Performances/ Computational Water, Energy, and Environmental Engineering 02(02):54-58, January 2013/ DOI:10.4236/cweee.2013.22006/ Open Access This is an Open Access article is distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0)

In 2021, scientists demonstrated a method of directly producing H₂ from air. This was achieved by capturing freshwater from the atmosphere using hygroscopic electrolyte and converting it to H₂ by electrolysis powered by solar energy. A prototype H₂ generator was successfully installed and operated for 12 consecutive days with a stable performance at an average Faradaic efficiency at around 95%. The so-called direct air electrolysis (DAE) module was found to be able to work under low relative humidity (20%) environment and also overcome water supply issues as well as produce green hydrogen sustainably with little negative effect on the environment. The DAE modules were also tested for scalability to different environmental circumstances and found to be able to provide H2 to remote, arid/semi-arid, and scattered areas.

Image: The concept of direct air electrolysis (DAE) for hydrogen production. a) A schematic diagram of the DAE module with a water harvesting unit made of porous medium soaked with hygroscopic ionic solution. b) Equilibrium water uptakes of hygroscopic solutions at different R.H.



Source: Gang Kevin Li, Jining Guo, Yuecheng Zhang, Ali Zavabeti/ Hydrogen Production from the Air/ The University of Melbourne, University of Western Australia, The University of Manchester/ DOI:10.21203/rs.3.rs-691931/v1/ Open Access This is an Open Access article is distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0)

The insights into the mechanism of the cobalt catalyst are truly remarkable. However, to further advance the catalyst performance, understanding the reaction mechanism at the atomic scale under electrolyser operating conditions was found to be of critical importance. So far, the team could analyse critical structural changes taking place in the catalyst under operating conditions by using X-ray analyses at the Advanced Photon Source (APS) at Argonne. They also identified key catalyst features using electron microscopy at Sandia Labs and at Argonne’s Center for Nanoscale Materials (CNM). As the main ingredient in the new catalyst is cobalt, it can be produced much more cheaply than by using iridium. In addition, computational modeling at Berkeley Lab revealed important insights into the durability of the catalyst under reaction conditions.

There is hope that this catalyst will form the beginning of clean hydrogen production and thus help mitigate human-induced climate change and pollution. In any case, the concerted efforts of Argonne Lab, Sandia Lab and Giner Inc. are certainly going to have a profound impact on future sustainable energy production methods.

By the Editorial Board