Is hydrogen the solution?
generation capacity of the system by replacing the added base with a material that also generates hydrogen. 10
Hydrogen fuel cells currently are not used widely, whether that be for power plants or in cars, due to their lack of development and high costs. One economic issue with hydrogen fuel cells is the use of a platinum catalyst around the electrodes, which makes up roughly 60% 11 of the cost of a single fuel cell. However, to combat this, Imperial researchers have developed a hydrogen fuel cell that uses iron, nitrogen and carbon materials as a catalyst instead of platinum, therefore reducing the cost of the technology greatly. Dr Asad Mehmood, from the Department of Chemistry at Imperial, says: We have developed a new approach to make a range of ‘single atom’ catalysts that offer an opportunity to allow a range of new chemical and electrochemical processes. Specifically, we used a unique synthetic method, called transmetallation, to avoid forming iron clusters during synthesis. This process should be beneficial to other scientists looking to prepare a similar type of catalyst. 12 The research team was aiming to produce a catalyst, where ‘iron would disperse as single atoms within an electrically conducting carbon matrix’. 13 Similar to silicon nanoparticles used in water splitting, a single-atom of iron has different chemical properties than a bulk of iron in which the iron is more reactive and boosts the reaction within the fuel cell. Another issue regarding hydrogen energy is the transportation and storing of hydrogen. Currently there are a few complications of a hydrogen economy, where existing infrastructure does not support hydrogen as a main fuel source; it is, after all, highly flammable and has many risks. Most importantly, hydrogen can be stored as either a gas or liquid, where the liquid form would require cryogenic temperatures since the boiling point of hydrogen is -252.8°C at one atmospheric pressure and would require a lot of energy to maintain those low temperatures. To deal with this, scientists have explored alternative ways of storing hydrogen such as a lithium-nitrogen-hydrogen storage system. In this system, lithium nitride reacts with hydrogen to form lithium amide and lithium hydride and will release hydrogen in the reversible reaction.
Li 3 N + H 2 ⇌ Li 2 NH + LiH
The reversible reaction for this type of hydrogen storage is currently still too slow to be made useful. However, researchers at Mahidol University of Thailand are trying to understand how each pore within the nanoconfined lithium-nitrogen-hydrogen system works to reveal how to eliminate intermediate species in the reaction, which can help increase rate of hydrogen uptake and release of hydrogen. Their team devised a method to nano-confine lithium nitride in a matrix of carbon to speed the reaction. The results of the experiment showed that smaller sized particles are unfavourable for the formation of
10 Lisa Zyga: https://phys.org/news/2013-01-nanosilicon-rapidly-electricity.html. 11 Hayley Dunning: https://www.imperial.ac.uk/news/235714/cheaper-hydrogen-fuel-cell-could-mean/.
12 Ibid. 13 Ibid.
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