@Stanford University Nickel-Iron Electrolysis Electrodes – How Oxides of Iron and Nickel herald Cheaper Electrodes All-Electric Vehicle

Hydrogen may be the fuel of the future as prophesied in my blog article entitled “PEM Fuel Cell Technology gets Japanese Government support - Hydrogen Gas Stations Coming in First World and Developing World Countries” but getting it to use in motor vehicles is not an easy affair.

This is to because electrolysis, a potentially easy way to produce Hydrogen from water, requires the use of expensive Platinum or Iridium Electrode and very large currents.

This may soon be a thing of the past, as researchers at Stanford University have figured out a cheaper material for the electrodes used in electrolysis of water and a catalyst that reduces the power needed as reported in the article “New device splits water into clean hydrogen and oxygen”, published June 30, 2015 By Nicolette Emmino, Digitaltrends. 

The research paper was written by Stanford graduate student Haotian Wang, who led the Stanford University study with assistance from Professor of Materials Science and Engineering at Stanford University, Yi Cui. Stanford graduate student Haotian Wang work builds on earlier research done by Stanford Graduate Student Hongjie Dai using Iron and Nickel as electrodes.

All of this sounds a bit overblown and very strange. Don't get me wrong, it's a very important development as published in the Stanford Newspaper article  “Single-catalyst water splitter from Stanford produces clean-burning hydrogen 24/7”, published June 23, 2015 BY MARK SHWARTZ, Stanford Report. But aren't these cheaper electrodes consumed when used in electrolysis?

Stanford graduate student Haotian Wang, who led the Stanford University study, opted to use electrodes composed of an alloy of Iron and Nickel. Iron and Nickel are usually consumed in the reaction, but apparently they must have treated the electrodes so that Nickel (I) Oxide (NiO_(s)) and Iron (II) Oxide (FeO_(s)) salts do not form during the electrolysis process.

So how did they do this?

Stanford University Nickel-Iron Electrolysis Electrodes – Oxides of Iron and Nickel

Using Rare Earth metals for Electrodes makes the process of electrolysis more expensive.

They're needed as any other type of metal for the electrodes for the Anode (+) Anode Cathode (-) will react with the Oxygen (O_{2 (g)}) gas to form oxides. Oxygen (O_2(g)) gas is formed at the Anode (+) while Hydrogen gas, which is relatively inert, will bubble off the Cathode (-) as follows:

1.      2H⁺ + 2e^- "H_2(g) (Reaction at the Cathode)

2.      O^2- " O_2(g) + 2e^- (Reaction at the Anode)

Electrolysis of water requires charge carriers in the form of ionic salts dissolved in the water, as pure water cannot be broken down by electrolysis. Also, to produce large volumes of both gases required larger voltages and currents, hastening the rate at which the electrodes were consumed as well as increasing the amount of electricity needed to perform electrolysis.

To overcome these problems, Stanford graduate student Haotian Wang may have opted to use oxides or sulphides of Iron and Nickel instead of the direct metals, as Iron and Nickel are normally consumed in electrolysis reaction.

These oxides may have been produced by reducing the Iron and Nickel down to nanoscopic powders that were very reactive and then introducing Oxygen (O_2(g)) at very low pressure in a vacuum chamber to react with the powdered nanoparticles of Iron and Nickel.

The resulting oxides or sulphides meant that the metals were made inert but non-conductive.

Oxides formed by oxidization means that all of the available electrons have been used in covalent bonds with Oxygen (O_{2 (g)}) or some other Group VI such as Sulphur (S_8(s)). To get them reactive, the Stanford Researchers then sintered the Iron and Nickel oxides together in a vacuum oven using either intense radiation or a strong electrical heating source.

While the powders were being heated and fused to form the electrodes, they also introduced a strong magnetic field while being slowly cooled. This ensured that as the metal cooled, the Nickel (I) Oxide (NiO_(s)) and Iron (II) Oxide (FeO_(s)) or Nickel (I) Sulphide (NiS_(s)) and Iron (II) Sulphide (FeS_(s)) formed orderly metallic crystals within their macromolecular structure.

Stanford graduate student Haotian Wang Black Salts – A Picture is worth a thousand Chemistry Equations

The result would not only be an electrode with possibly some amount of paramagnetism, but also highly conductive, as the electrons would flow more easily through the metallic crystal Lattice which has an orderly arrangement of Nickel (I) Oxide (NiO_(s)) and Iron (II) Oxide (FeO_(s)) salts.

This explains why the electrodes shown in the picture above with Stanford graduate student Haotian Wang are black in colour; they're black because they're possible oxides or sulphides of Iron and Nickel.

Because he’s improving upon the work of Stanford Graduate Student Hongjie Dai, he may have combined the Nickel (I) Oxide (NiO_(s)) and Iron (II) Oxide (FeO_(s)) or Nickel (I) Sulphide (NiS_(s)) and Iron (II) Sulphide (FeS_(s)) into a single electrode via sintering, based on how well those previous experiments went to quote Stanford graduate student Haotian Wang: “Our water splitter is unique because we only use one catalyst, nickel-iron oxide, for both electrodes”.

Good to note here it is Iron (II) Oxide (FeO_(s)), a black salt and not Iron (III) Oxide (Fe₂O_3(s)), a red salt, often called rust, as rust has little or no catalytic properties. Same too for Nickel (I) Oxide (NiO_(s)) or Nickel (I) Sulphide (NiS_(s)), both of which are black salts.

Iron and Nickel are Catalysts - Cheaper Electrodes All-Electric Vehicle Electrodes Special Treatment

Aside from this fabrication method using Nickel (I) Oxide (NiO_(s)) and Iron (II) Oxide (FeO_(s)) or Nickel (I) Sulphide (NiS_(s)), Iron and Nickel both have known catalytic properties. These metals by themselves are known Catalysts. 

Like a good catalysts, it lowers the activation energy required for a chemical reaction to take place or in this case, breaks the bonds by supplying the energy to overcome the covalent bonds between the Hydrogen and the Oxygen (O_2(g)) molecules without being consumed in the reaction.

Iron is used as a catalyst in the Fitz-Haber Process to make Ammonia (Lambert & Mohammed, 1993 pp. 187) on an industrial scale and Nickel is used as a catalyst in the production of margarine from Coconut oil in the form of Raney Nickel (Hill & Holman, 1989, pp. 504) to produce Cyclohexane from Benzene. 

The fact that electrolysis requires a 1.5V battery source suggests that the battery is acting as an electron charge pump, pumping extra electrons into the reaction and thus speeding it up. Since the sintered using Nickel (I) Oxide (NiO_(s)) and Iron (II) Oxide (FeO_(s)) or Nickel (I) Sulphide (NiS_(s)) is as very good conductor due to the fabrication process, this explains why the reaction can take place at such a low voltage.

Stanford graduate student Haotian Wang research has not only made the traditional electrolysis more efficient, but his research suggests that the oxides of transition metal catalyst can be used in lieu of Rare Earth Metals for Batteries electrodes in All-Electric Vehicles.

All that is required is that the process by which the metal is prepared so as to change the properties of the metal to make it more conductive and less reactive, while taking advantage of its catalytic properties.

References:

1. Lambert, N., Mohammed, M. (1993). Chemistry for CXC. pp.187, Jordan Hill, Oxford: Heinemann
2. Hill, G.C., Holman, J.S. (1989). Chemistry in Context. (3rd Ed.). pp. 504, Surrey, UK: Thomas Nelson and Sons Ltd