Revolutionary Photocatalyst - Great News for Green Hydrogen and Ammonia
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Revolutionary Photocatalyst is great news for chemistry as it promises to unlock ammonia as a clean fuel. Further, it can help decarbonize the entire chemical industry in the process. 

The researchers at Rice University have created a small, LED-powered device. The device helps convert ammonia to hydrogen on the fly with the use of a light-driven catalyst. The good news is it’s as efficient as the expensive thermal catalysts which require thousand-degree temperatures to operate. It’s manufactured from cheap, abundant copper and iron. The cost of the device and its energy usage will go down considerably as still in its early stages.

Hydrogen is a strong, clean-burning fuel. When it burns or is used in a fuel cell, it creates electricity. The downside is that hydrogen is a transcendent gas that must be compressed to 700 atmospheres to become liquid, so it’s both expensive and difficult to handle.Revolutionary Photocatalyst - Great News for Green Hydrogen and Ammonia_1Ammonia is known to be a better hydrogen carrier than hydrogen gas itself. It binds 3 atoms with each of its nitrogen atoms. It is caustic and extremely hazardous in high concentrations but is at room temperature and pressure to be stable as a liquid and we have plenty of experience in handling it safely under conditions range wide.

Even though Ammonia carries hydrogen exceptionally well, you will need to break it down before using it, in the process releasing the harmless nitrogen back into the atmosphere. It is not easy to achieve this for two reasons. First of all the reaction is endothermic, it needs to be broken down in huge facilities operating in temperatures ranging from  650-1,000 °C (1,200-1,800 °F) at least. 

The second reason being the thermal catalysts required for breaking it down is platinum-group metals like ruthenium which are rare and expensive. The researchers at Rice University are excited with that discovery as it offers a compact and efficient way to catalyze this cracking reaction at room temperature just using copper and iron.Revolutionary Photocatalyst - Great News for Green Hydrogen and Ammonia_2Antenna-reactor plasmonic photocatalysts are a new technology created by Dr. Yang’s team that targets molecules in the air to help catalyze important chemical reactions. This is achieved by bonding the catalyst material with an antenna, which provides a means for it to absorb light and produce the desired type of electrons at a level greater than other surface-enhanced chemistry systems. These antenna-reactor particles can be tuned for optimal performance outside.

This ammonia-splitting photocatalyst uses iron as its reactor, and copper as its light-collecting antenna. Iron is a cheap and abundant metal, unlike the usual copper-ruthenium thermal catalysts used today in lab testing. According to Rice alum Hossein Robatjazi, “under illumination, the copper-iron showed efficiencies and reactivities that were similar to and comparable with those of copper-ruthenium.”

Initial tests were conducted using light supplied by lasers, in a tiny experimental setup. However, study co-author Naomi Halas is also the co-founder of Syzygy Plasmonics, a well-funded company that is able to take this technology commercial and has built a test rig (using LEDs instead of lasers). The catalyst remains just as efficient.Revolutionary Photocatalyst - Great News for Green Hydrogen and Ammonia_3Halas added, “This is the first report in the scientific literature to show that photocatalysis with LEDs can produce gram-scale quantities of hydrogen gas from ammonia. This opens the door to entirely replace precious metals in plasmonic photocatalysis.”

This copper-iron photocatalyst can be used to extract hydrogen from ammonia and do it cheaply. In addition to being easier and cheaper, there will also be less energy and emissions required.

Much more importantly, this could lead to a device that’s small, reliable, and lightweight – even cooler than the last one. Something that doesn’t need a large-scale facility to operate. Syzygy says its initial Rigel Photocatalytic Reactor is about the size of a small washing machine, and processes around a ton of material per day – depending on the specific chemical reaction it’s running. These can be stacked; you can run multiple devices simultaneously if you need greater output.

Might there be such an application for a bank of these on an electric cargo ship? It would turn ammonia into hydrogen to provide the fuel right where it’s needed. That in itself would be revolutionary because cleaner ships like this could revolutionize shipping ranges.

What if this small and lightweight technology could be used for aviation? Imagine the possibilities: a hydrogen fuel cell that could power airplane ranges that are currently out of reach without jet fuel. What’s more, it would offer the potential to replace rocket fuels on space flight missions. Eventually, this technology might even become small enough to take with you wherever you go- such as to an electric car charging station or a gas station where ammonia is readily available.

And just this photocatalyst isn’t enough to do the job – Rice and Syzygy want to disrupt the thermal catalyst market wherever they can.

“Given their potential for significantly reducing chemical sector emissions, plasmonic antenna-reactor photocatalysts are worthy of further study,” added Emily Carter, another author. “These results are a great motivator. They suggest it is likely that other combinations of abundant metals could be used as cost-effective catalysts for a wide range of chemical reactions.”Revolutionary Photocatalyst - Great News for Green Hydrogen and Ammonia_4Co-author and Syzygy co-founder Peter Nordlander said, “Catalysis is the foundation of the chemical industry and it’s one of the most energy-consuming parts of all society.”

In this research Halas shows that LED-based chemistry is actually doable and can contribute to industrial-scale chemistry at scale. It can be used for industrially important reactions, too.

Syzygy has said that it is already performing field trials on photocatalytic ammonia-cracking reactors, and they expect to have this product commercially available in 2023.

This is some innovative technology that has huge potential across a variety of industries.

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