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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."
Use against terrorism: Set up enough of the tubes and you can detect when a hydrogen bomb goes off there (assuming they survive).
I think titania here is titanium dioxide, TiO2, which is most commonly used as a pigment- most opaque white pigments contain titanium dioxide, also known as rutile. I had no idea you could make it into nanotubes though.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
I'm still at a loss as to how detecting hydrogen helps combat terrorism. Would someone care to enlighten me?
Video Game cheats, hints a
Hydrogen entering an array of titania nanotubes flows around all the surfaces, but it also splits into individually charged atoms and permeates the surface of the nanotubes. These hydrogen ions provide electrons for conductivity. The change in conductance signals that hydrogen, above the background level, is present.
Sounds very similiar to how a fuel-cell works, but instead of pumping through lots of hydrogen to produce as much electricity as possible they're just using a little bit of hydrogen to generate a tiny current (or does it just change the conductivity?).
I want to know what this material does when feed pure hydrogen.
I am too lazy to figure out valences but a
quick google shows that theoretical calculations
predict them to exist and be semiconducting,
and someone has done TEM of those tubes so they
do exist and have been characterized. That said,
you'll have to look deeper for more info cause
I don't really care.
BTW, most oxides and dichaclogenides which exist
in layered crystal structures can be "rolled" up
and form nanotubes.
As a muslim I must correct you. A more correct transliteration would sound like this. Allah-huu-akhbar. (key part you missed being the huu which sounds like who).
If anyone wants to know what that means... it's simply god is great or allah is great. Technically allah isn't a god as there is no sex associated with allah (god implies a masculine deity).
Hmmm... Pie...
Nothing, "by itself" burns. There is always a fuel and some kind of oxidiser. The hindenburg burned very fuel rich, but if the hydrogen in it had been mixed with enough oxygen, it would have flattened everything in sight when it went up.
When it DOES burn, it burns a)instantly
Yeah, think explosion.
b)practically invisibly, c)with no smoke. Watch those films of the hindenburg, and note the a)slow b)bright yellow c)sooty fire.
Classic features of a fue-rich 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.
In open air, yes. But the scenario I'm worried about is when it happens somewhere semi-enclosed, like a parking garage, or a tunnel. Some kind of area where the hydrogen can't quickly escape upwards, but has time to form an explosive mixture with the air. In a parking garage under other buildings it seems like it would be pretty devastating, but I haven't seen that scenario discussed anywhere.
"An object declared as type _Bool is large enough to store the values 0 and 1." -- 6.1.2.5, C99 standard.
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.