Titania Nanotubes for Hydrogen Sensors?

Roland Piquepaille writes "Everybody is talking about carbon nanotubes these days. But what about titania nanotubes? Penn State researchers think they have a great potential for sensing hydrogen . According to this news release, "titania nanotubes are 1500 times better than the next best material for sensing hydrogen and may be one of the first examples of materials properties changing dramatically when crossing the border between real world sizes and nanoscopic dimensions, according to a Penn State materials scientist." And now, the very good news: titania nanotubes are cheap. So they'll be used in industrial quality control in food plants and as weapons against terrorism. My summary contains some more details."

Comments

Terrorist detection

[macragge]

Now we will be able to detect the terrorists at they attempt to crash Zeplins into our buildings!

Re:Terrorist detection

[AntiOrganic]

Stop terrorists?

Saddam Hussein tried to buy titania nanotubes from Africa!

Re:What the hell is titania?

[soundnfury]

Screw titania. When are they gonna get the kryptonite nanotubes?

Better tools

[Stonent1]

A lit match works for hydrogen detection as well as many gas hydrocarbons. It is very versatile.

cheap?

[HBI]

How cheap could these be? I mean titanium itself is not a cheap metal (about $4 a pound apparently), but I imagine making nanotubes out of titanium oxide probably does not consume much titanium. The process has to be a bitch though.

I don't see anything about cost in the paper either.

Overexuberance on the author's part?

Re:cheap?

[Anonymous Coward]

First of all, the article sounds like a hoax to me.

But regarding the price of titanium:

Titanium metal is expensive. Titanium oxide is not.

Most elements do not like to be turned into metallic form. So although aluminum is the most abundant element in the Earth's crust, nevertheless, iron and steel are much cheaper (by weight) than aluminum.

Re:cheap?

[hcetSJ]

Although I don't know what the process is, the fact that titania is a ceramic means that there is probably some creative chemical conditions in which these things practically make themselves (sol-gel process, maybe). Ceramics are generally covalent networks--each atom is connected to the next with a bond like those which hold hydrogens to oxygens in water--and so by changing the conditions under which the titanium oxidizes, you probably have fairly good control over the size/shape of the final result. Not so with carbon nanotubes, which were originally manufactured pretty much by sifting through ashes...with an electron microscope. I know there are some more creative ways to make carbon nanotubes now, but most of them are still based on chance.

Maybe someone who has actually received a BS in Materials Science wants to back me up, or correct me?

Re:cheap?

[Goldsmith]

Well, I don't have a BS in Materials Science, but I'm working on a PhD in... well, lets call it nanoscience.

I personally don't know how to make titanium oxide nanotubes, but I imagine it would be similar to making carbon nanotubes... which I do have experiance with.

Allow me to show you...

The way you make carbon nanotubes is simple. You start with a catalyst (everything from rust to specially tailored alloys has been used), place this catalyst on a clean substrate where you want the tube to start growing. Next, flow some carbon rich gas through a furnace (i.e. methane), add a little hydrogen. When hot, place your substrate in the furnace. Nanotubes will grow from the catalyst in the direction of the flow (mostly).

That same method is used to grow many types of tubes and nanowires. The only hard thing is dealing with flammable and explosive gases at high temperature (I havn't blown anything up yet, but I'm trying), and keeping everything clean.

When dealing with nanotubes, you have to remember that you want to get a specific shape out, and not amorphous material, and that can be very hard. In most cases, you tailor your catalyst to provide the general shape you want, and grow off of that. So you could very easily control the growth of a ceramic, but the shape?

Now obviously, there are other ways to grow these things... but I'm going to stop now before this turns into a lecture.

Terrorism?

[roman_mir]

Why everything has to be about terrorism?
1. Throw around a buzzword, like nanotubes.
2. Mention fighting the terrorism.
3. Well, we all know what comes at step 3, don't we?

This is why everything has to be about terrorism.

Allah Akbar = Profit?

---------
(I used Allah Akbar not because I think it is in itself pro-terrorist, but because it is the most recognized token for the situation, so please.)

WTF is Titania?

[SiliconEntity]

Titania, it turns out, is Titanium Dioxide, used commonly as a white pigment. Read more about it at the Wikipedia.

Re:What the hell is titania?

[luzrek]

Titania is also the name of the well-endowed barmaid in the episode of the Simpsons where Moe has Plastic Surgery.

Seriously though, this press-release sets off my B.S. sensor. A typical scientific press-release would include some basic stuff, like what Titania Nanotubes are. Additionally, from my understanding of how carbon nanotubes are made, and how they exist, I'm not sure that Titanium could be used to make nanotubes. Neither could Silicon, which is the chemically more similar. Carbon nanotubes can exist because Carbon gets to form 4 and only 4 bonds. The extra electron orbitals (d-orbitals in spectroscophy language) would screw this up.

Additionally, I don't think that combustion (say in cars, mentioned in the article), results in any free hydrogen, it should be water, carbon dioxide, and unburnt fuel.

Wonder what's the next best material?

[Anonymous Coward]

titania nanotubes are 1500 times better than the next best material for sensing hydrogen

Oxygen?

Hmm....

[lukew]

My daughter's name is Titania, sounds like she's been getting up to some serious mischief.

yeah

[nomadic]

Everybody is talking about carbon nanotubes these days.

Yeah, can't walk down the street or ride a subway without hearing that incessant chatter about carbon nanotubes.

Re:yeah and Please forgive the lengthness of my re

[agrippa_cash]

Well, sir, there's nothing on earth Like a genuine,Bona fide,Electrified, Titaniafied, Nanotube! What'd I say? Ned Flanders: Nanotube! Lyle Lanley: What's it called? Patty+Selma: Nanotube! Lyle Lanley: That's right! Nanotube! Miss Hoover: I hear those things are awfully loud... Lyle Lanley: But tt detects hydrogen clouds. Apu: Is there a chance the tube could bend? Lyle Lanley: Not on your life, my Hindu friend. Barney: What about us brain-dead slobs? Lyle Lanley: You'll be given cushy jobs. Abe: Were you sent here by the devil? Lyle Lanley: No, good sir, I'm on the level. Wiggum: The ring came off my pudding can. Lyle Lanley: Take my pen knife, my good man. I swear it's Springfield's only choice... Throw up your hands and raise your voice! All: Nanotube! Lyle Lanley: What's it called? All: Nanotube! Lyle Lanley: Once again... All: Nanotube! Marge: But Main Street's still all cracked and broken... Bart: Sorry, Mom, the mob has spoken! All: Nanotube! Nanotube! Nanotube! [big finish] Nanotube! Homer: Nano... D'oh!

Re:Titania in the war against terrorism

[ratfynk]

Simple, hydrogen molecules in explosives give off distinct hydrogen emmision signatures, hydrogen concentration loss has a very specific profile when used in combination with nitrogen in explosives. This is very quantifiable. It is also why older explosives became unstable over time. The loss of hydrogen molecules over time caused decay separation of the explosive component and the buffer. Some explosives even give off amonia, and some are made with it, Amex for example, the stuff used by Timothy McVie. If better explosive detection devices can come from this tech great! Then there is one more hurdle for social disfunctional maniacs to overcome.

Annoying learn-about-hydrogen comment

[SuperBanana]

And now for your entertainment tonight, the obnoxious nitpicking Slashdot comment reply!

A lit match works for hydrogen detection as well as many gas hydrocarbons.

Actually, Hydrogen requires a higher fuel to air ratio than gasoline. It also disperses nearly instantly(well, except in confined/sealed areas of course)- whereas gasoline etc sink and pool(which is why your natural gas/propane water heater has that nice little picture of a gasoline can etc).

Oh, and since it's still not known enough- the Hindenburg burned because it was painted with the chemical equivalent of rocket fuel(the chemical composition of the paint etc is very close to solid rocket fuel)- not because it was full of Hydrogen, which, by itself, doesn't burn.

When it DOES burn, it burns a)instantly b)practically invisibly, c)with no smoke. Watch those films of the hindenburg, and note the a)slow b)bright yellow c)sooty fire.

It's interesting to note that hydrogen's qualities make it much safer should there be, say, an accident with a truck carrying it. It dissipates as it leaks, versus the major fire hazard/toxic waste problem created by a gasoline spill.

Size and electron affinity

[fven]

There are two things that are of help here. Firstly is the size of the tubes, when you are in the nano- or pico- regimes, there are a lot more surface features (corners, edges) per atom than there are in the bulk metal. As most reactions (catalytic or non catalytic) occur on surface features, having as many small particles as possible makes sense.
The other factor that is a help here is that the oxide is used. Introducing impurities into metal (consider the oxygen an impurity) does two things, changes the electron affinity of the metal so it can bind ligands better (or worse - also useful) and introduces point 'defects' - places where the crystal lattice is interrupted. These 'defect' sites actually provide reaction points for in this case, hydrogen.
Nice piece of chemistry!