Breakthrough in Green Hydrogen Substitutes Water for Iridium

Hydrogen holds potential as a potent, eco-friendly fuel source, provided its production process is also environmentally sustainable. A recent report highlights the challenges in achieving genuinely green hydrogen, while a new study overcomes a hurdle in its production.

According to a study released today in the journal Nature Energy, authored by Kiane de Kleijne from Radboud University and Eindhoven University of Technology in the Netherlands, hydrogen production frequently results in increased atmospheric carbon dioxide (CO2) emissions. This is partly due to the involvement of natural gas production.

Challenges of Green Hydrogen Production and Global Distribution

There are more environmentally friendly methods to produce hydrogen, such as using solar or wind energy to power the process of extracting it from water molecules. However, De Kleijne contends that in such cases, the carbon footprint of establishing these facilities must be taken into account.

Additionally, the effectiveness of green power is highest in regions abundant in sunlight and wind, such as Africa or Brazil. Consequently, hydrogen produced in these areas must be transported globally for use, which can increase its carbon footprint.

“When you consider the entire life cycle in this manner, green hydrogen often results in reduced CO2 emissions, although not always,” De Kleijne explained. “The reductions in CO2 emissions are typically greater when wind power is used rather than solar power. This trend is expected to improve further as more renewable energy is utilized in manufacturing components like wind turbines, solar panels, and electrolyzer steel.”

A recent advancement in a widely used hydrogen production method known as proton-exchange-membrane (PEM) could offer a solution in the meantime.

PEM Electrolysis and the Challenge of Iridium Availability

PEM involves electrolyzing water to separate hydrogen molecules, with its environmental friendliness hinging mainly on the carbon footprint of the electricity used. It’s considered green because it produces only oxygen as a byproduct, not carbon dioxide.

However, the challenge lies in the use of iridium, one of the few elements capable of withstanding the harsh acidic conditions required for splitting water molecules. Given iridium’s extreme rarity, being one of the Earth’s scarcest metals, scaling up PEM facilities has proven difficult.

Introducing a recent study from the Institute of Photonic Sciences (ICFO) in Spain, which is elaborated on in the accompanying video.

Development of Anode Catalysts with Cobalt and Tungsten at ICFO

In essence, researchers at ICFO developed an anode catalyst using more readily available elements, cobalt and tungsten. To safeguard the anode from anticipated degradation during the electrolysis process, they took an innovative approach by incorporating a cobalt-tungsten oxide with water – the very medium in which it operates.

“At the outset of the project, we were intrigued by the potential role of water itself as a significant factor in water electrolysis,” explained Ranit Ram, the study’s lead author. “No one had previously tailored water and interfacial water in this manner.”

As a result, during electrolysis, as the new anode underwent degradation and material loss, water and hydroxide – both integral compounds in the process – flowed in to fill the voids it created. This created a protective aqueous barrier that slowed the anode’s degradation rate.

In PEM reactor tests, the new material demonstrated significant achievements.

“We achieved a five-fold increase in current density, reaching 1 A/cm2 – a notable milestone,” said Dr. Lu Xia, a co-author. “Moreover, we maintained stability for over 600 hours at this high density, marking a record for non-iridium catalysts.”

While acknowledging the new water-impregnated alloy’s shorter stability compared to current anodes, the researchers underscore its effectiveness in showcasing a PEM approach independent of rare metals. They highlight the potential for this process to utilize alternative materials, addressing concerns about cobalt, which is often associated with ethical issues related to mining practices.

“Cobalt, while more abundant than iridium, raises significant ethical concerns in its sourcing,” explained ICFO professor García de Arquer. “This motivates our exploration of alternatives like manganese, nickel, and various other materials across the periodic table as part of our catalyst development strategy.”

Read the original article on: New Atlas

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