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Platinum's clean energy breakthrough

Metal Tech News - May 8, 2024

Japanese researchers unveil platinum electrode enhancement for producing clean hydrogen.

Imagine a world where clean energy is not just a dream but a reality. Researchers at Chiba University have taken one step closer by cracking the code on platinum electrodes that are vital to hydrogen fuel cells and electrolysis. With subtle changes to the way these electrodes interact with water, they've discovered a game-changing method to boost both efficiency and durability – a small tweak with big implications for the planet's future.

The pursuit of carbon neutrality has driven the exploration of numerous clean energy sources and alternatives, with hydrogen fuel cells emerging as a promising replacement for petroleum-based combustion due to their similar functionality.

Also known for its explosiveness, which could provide the necessary power to replace fossil fuel burning in vehicles, the most beneficial byproduct of a hydrogen-fueled vehicle would be a tailpipe that outputs pure water rather than toxic emissions.

In hydrogen cells, hydrogen undergoes an electrochemical reaction with oxygen to produce electricity and water. Conversely, the reverse of this process, called electrolysis, can be used to split abundantly available water to produce hydrogen used as clean-burning fuel.

These two technologies could provide not only abundant clean energy but also be renewable and self-sustaining if taken to the extreme of efficiency.

The crux, however, is that these two technologies rely on platinum or other catalysts.

Challenges in fuel cells

Hydrogen fuel cells consist of two electrodes, an anode and a cathode, with an electrolyte between them – similar to a battery.

Platinum serves as a fundamental catalyst in low-temperature fuel cells, and because it serves as the best ingredient for an oxygen reduction reaction, which is crucial for fuel cells, research has been limited due to the high costs and limited availability of this precious metal.

Further, certain chemistries lead to oxide formation on the surface of the cell, which eventually roughens and dissolves the platinum layer, ultimately degrading the cathodes and affecting performance and stability.

Unraveling how surface oxides form is crucial for crafting platinum catalysts. Just as different ingredients affect how bread bakes, factors like electrode potential, electrolyte, and the arrangement of charged particles near these oxides on platinum surfaces all play a key role.

While scientists have explored certain aspects of this, a complete understanding of the broader picture awaits discovery.

Advancements in alkaline

Professor Masashi Nakamura and his team at Chiba University in Japan are at the forefront of a discovery that could solve the platinum electrode degradation problem.

"In a previous study, we reported that interfacial hydrophobic ions with long alkyl chains can enhance ORR (oxygen reduction reaction). This suggests that it is possible to construct an interfacial reaction field that not only activates the ORR but also improves the durability of Pt (platinum) electrodes by using optimal interfacial ions," explains Nakamura.

In simpler terms, earlier work revealed that certain types of "oily" ions, which repel water, can actually improve how well platinum electrodes work as a catalyst. This means that by choosing the right ions, the reaction can be made to happen more efficiently, and it helps the electrodes last longer.

To do this, the team examined how different ions affect oxide formation on platinum surfaces in alkaline solutions.

Using advanced techniques, they found that some ions, like lithium ions, help stabilize certain oxides, preventing damage. While surprisingly, others like tetramethylammonium ions, also protect the surface, similar to lithium ions.

They also noticed that certain ions help remove platinum from the surface.

These findings underscore the importance of selecting the right ions to control oxide formation on platinum surfaces, a key factor in developing high-performance catalysts.

As Nakamura emphasizes, understanding these mechanisms is vital for creating stable electrocatalysts for future devices. Ultimately, this study brings us closer to realizing a zero-carbon future fueled by clean and abundant hydrogen.


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