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Saturday, 14 December 2019

Scientists discovered cheaper way to make hydrogen from water


Researchers have discovered a cheaper way to make hydrogen from water: a team of scientists led by the UNSW has demonstrated a sustainable way to get hydrogen, which is necessary, among other things, for fueling vehicles hydrogen.



Scientists from UNSW Sydney, Griffith University and Swinburne University of Technology have demonstrated that the capture of hydrogen by separating it from oxygen in water can be done using low-metals cost like iron and nickel (as catalysts), which speeds up the chemical reaction, while requiring less energy.

It should be noted that iron and nickel, which are found in abundance on Earth, would replace ruthenium, platinum and iridium, precious metals which until now have been considered as reference catalysts in the process of "Water fractionation".



Professor Chuan Zhao, of the UNSW School of Chemistry, explains that in water fractionation, two electrodes apply an electrical charge to the water, which allows the hydrogen to be separated from the water. 'oxygen. It can then be used as an energy carrier in a fuel cell.

“ What we do is coat the electrodes with our catalyst to reduce energy consumption. On this catalyst, there is a tiny nanoscale interface where iron and nickel meet at the atomic level, which then becomes an active site for water separation: this is where hydrogen can be separated from oxygen and captured as fuel, and oxygen can be released as environmentally friendly waste,” he explains.

Iron and nickel, but on a nanometric scale

Already in 2015, Professor Zhao's team invented a nickel-iron electrode for generating oxygen with unprecedented efficiency. However, Zhao believes that iron and nickel alone are not good enough catalysts for the generation of hydrogen, but that it is when they meet on the nanometric scale that the “magic operates ".

Nanoparticle design and electron microscopies. a Schematic representation of the Ni and Fe nanoparticles and the Ni-Fe Janus nanoparticles synthesis through the oleate-assisted micelle formation and the illustration on the HER across the Ni-γ-Fe2O3 interface in alkaline medium. b STEM-HAADF image of a single Ni–Fe NP nanoparticle and its corresponding EDS line-scan spectrum (scale bar: 1 nm). c High-resolution EDS mapping on STEM-HAADF images of the nanoparticles for Ni and Fe, selected area electron diffraction inset (image scale bars: 20 nm; SAED scale bar: 2 nm−1).


The nanoscale interface fundamentally changes the properties of these materials. Our results show that the nickel-iron catalyst can be as active as platinum in the generation of hydrogen,  ”he explains. "  An added benefit is that our nickel-iron electrode can catalyze both hydrogen and oxygen generation, so not only could we reduce production costs by using elements that are abundant on Earth, but also allow the use of one catalyst instead of two . ”

And indeed: a quick glance at current metal prices clearly demonstrates why this could be the change needed to accelerate the transition to the so-called hydrogen economy. Iron and nickel are priced at € 0.12 and € 19.65 per kilogram respectively. On the other hand, ruthenium, platinum and iridium are priced at € 10.6, € 37.9 and € 62.6 per gram respectively. In other words, thousands of times more expensive.



“ Right now, in our fossil fuel economy, we have this great incentive to move to a hydrogen economy so that we can use hydrogen as a clean and abundant energy carrier on Earth. Many people have been talking about the hydrogen economy for ages, but this time it seems like it really does happen  , "said Professor Zhao.

According to him, if water separation technology is developed, there could one day be hydrogen refueling stations (just like the service stations we know today), where we could refuel our hydrogen vehicles with hydrogen produced by this water division reaction. This could be done in a few minutes, compared to recharging hours in the case of electric cars with lithium battery.


Bibliography:

Overall electrochemical splitting of water at the heterogeneous interface of nickel and iron oxide
Bryan H. R. Suryanto, Yun Wang, Rosalie K. Hocking, William Adamson & Chuan Zhao

Nature Communications volume 10, Article number: 5599

http://dx.doi.org/10.1038/s41467-019-13415-8

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