> That is what makes the finding so striking. Manganese is usually not viewed as a friend of stainless steel corrosion resistance. In fact, the prevailing view has been that manganese weakens it.

> "Initially, we did not believe it because the prevailing view is that Mn impairs the corrosion resistance of stainless steel. Mn-based passivation is a counter-intuitive discovery, which cannot be explained by current knowledge in corrosion science. However, when numerous atomic-level results were presented, we were convinced. Beyond being surprised, we cannot wait to exploit the mechanism," said Dr. Kaiping Yu, the first author of the article, whose PhD is supervised by Professor Huang.

This is the Cannot be explained bit

• adrian_b

  today at 10:31 AM

  A bonus is that manganese is one of the cheapest metals, so this method for increasing the corrosion resistance of stainless steel in salted water and oxidizing conditions is very inexpensive.

The "cannot be explained" headline is a bit much, but the underlying result is genuinely interesting

So apart from the clickbait, the reason why this is interesting is because it's a limiter for the often cited idea of clean green hydrogen from electrolyis. The current use of titanium and precious metals is, obviously, really expensive, so it's uneconomical to build something that only runs on "spare" electricity.

• londons_explore

  today at 9:38 AM

  I don't think the efficiency or longevity of electrolysis equipment is the limiting factor...

  The limiting factor is that natural gas is very cheap and cracking it to make blue hydrogen is really easy at scale, and gives off CO2 which is useful for injection into wells to increase production. That sets a price ceiling of hydrogen.

  At the other end of the scale, there are batteries to store 'free' electricity and resell later. That sets a floor price of electricity.

  Between the floor price of the input and ceiling price of the output, there is no room for electrolysis, even at 100% efficiency, unless government policies mandate it or restrict batteries or blue hydrogen.

  • leonidasrup

    today at 10:17 AM

    Sometimes the price of natural gas is even negative, there is too much of it.

    "Natural gas at Texas’s Waha hub is trading at negative $7.05 per million British Thermal Units, hitting a record low of negative $9.52 on April 15."

    https://www.barrons.com/articles/natural-gas-texas-negative-...

    There are different kinds of water electrolysis equipment, with different capital expenditure and operating expenses.

    "Alkaline electrolyzers are cheaper in terms of investment (they generally use nickel catalysts), but least efficient. PEM electrolyzers are more expensive (they generally use expensive platinum-group metal catalysts) but are more efficient and can operate at higher current densities, and can, therefore, be possibly cheaper if the hydrogen production is large enough."

    https://en.wikipedia.org/wiki/Electrolysis_of_water#Efficien...

    Anything using platinum-group metals will be very expensive. Therefor catalytic converters in cars use very little platinum-group metals.

    "The amount of palladium in a converter can vary, but it is typically around 2-7 grams." https://vehiclefreak.com/how-much-palladium-is-in-a-catalyti...

  • pjc50

    today at 10:27 AM

    > unless government policies mandate it or restrict batteries or blue hydrogen

    Yes, but I think this the most likely outcome. Natural gas is only cheap in certain areas, and the past few years have made everyone very, very aware of the geopolitics involved in getting hold of it. While global warming is not going away, and I question the extent to which CCS actually happens with blue hydrogen.

    Batteries are capital equipment in the same way as electrolysers are. They're great at short term storage, but medium-term is still a bit more of an issue. "Restrict batteries" is obviously not on the table except for stupid retail corner cases where utilities have captured the regulator.

    There's a potential market for lots of green H2 in Haber nitrogen, metals refining, and synthetic jet fuel etc, but only if the cheap CO2 emitting option is priced out or banned, or H2 electrolysers get comparable capital prices to battery storage.

    • leonidasrup

      today at 11:02 AM

      With CO2 emitting option is priced out or banned, direct hydrogen production using high temperature sulfur–iodine cycle without H2 electrolysers could be economic option. The heat could be supplied from high temperature nuclear reactor.

  • Tuna-Fish

    today at 10:21 AM

    Reducing the capital cost of electrolysis is extremely good, because it makes plants that only produce when electricity is cheap (midday in sunny climes, when wind is blowing in the Nordics) more feasible.

    If this works out at scale (lots of problems can be found between a lab discovery and mass production), this is legitimately a very good thing for renewables.

  • whizzter

    today at 10:01 AM

    There's one case, rural areas often have abundant energy sources (hydro, wind,etc) but few consumers, in Northern Sweden f.ex. a lot is produced but there's a lot of losses in transporting the energy south.

    Now, yes, as long as natural gas is cheap(inbetween US or Soviet wars) it'll probably be the core for hydrogen, however batteries won't help much in the north since the transmission rather than usage is the cap even with batteries so excess production could be redirected towards hydrogen production.

• SwtCyber

  today at 10:23 AM

  Yes, although I'd still want to see how much of total delivered hydrogen cost this actually moves

You just know that engineers and management in Toyota's delusional hydrogen division are salivating.

• adrian_b

  today at 10:35 AM

  Nope.

  Splitting water into free hydrogen and oxygen is important because it is an essential step for using electrical energy in the chemical and metallurgic industries.

  For long term energy storage, free hydrogen is not a good solution, but it can be used to synthesize hydrocarbons, which are suitable for long term energy storage or for aerospace transportation.

  Even with abundant and cheap dihydrogen, using it for energy storage in vehicles is a bad idea.

> This second shield helps protect the steel in chloride containing environments up to an ultra high potential of 1700 mV.

Uh, dumb question, how is 1.7 volts "ultra high potential" ? Is that even enough to do electrolysis like they're talking about?

• manarth

  today at 9:28 AM

  Galvanic corrosion typically happens at 0.5V (and as low as 0.15V in salt-water); 1.7V is "ultra high potential" in comparison with normal corrosion thresholds.

• Tuna-Fish

  today at 10:18 AM

  The potential needed for electrolysis of water is 1.23V in theory, in practice a bit more to overcome inefficiencies. 1.7V is enough.

• ajb

  today at 9:25 AM

  I think that may not be the potential used for electrolysis, but the chemical potential of the saltwater-metal boundary. But hopefully someone more knowledgeable will comment.

• today at 10:04 AM

this kind of headline is bad for our collective souls; I know raging against the clickbait is old hat but seriously, this is ridiculous. Materials science is surely interesting enough to a reader of science direct without being SHOCKED and APPALLED all the time

So does carbon, no?

• SwtCyber

  today at 10:24 AM

  Sometimes, but carbon has its own failure mode: at high anodic potentials it can oxidize

@dang maybe we could have the title changed to something like

"Hong Kong researchers develop corrosion-resistant steel for seawater hydrogen electrolysis"

• tomhow

  today at 9:38 AM

  Thanks! That's too long (limit is 80 chars) but I came up with something that fits. Feel free to suggest something better.

  • sveme

    today at 9:44 AM

    I think the seawater bit is really relevant here. Only understood the importance of this when I saw the seawater part.

    • tomhow

      today at 9:47 AM

      OK, how about that?

• greenbit

  today at 9:31 AM

  I'd click on that