Summary:
As you watch the video, listen to what Rachel has to say about:
Captions:
So let’s have a look at what I’m doing. I work with materials chemistry.
So basically as a chemist I’m looking at things on the atomic scale.
So I’m looking at how do I place this atom with this atom during the actual synthesis.
So the synthesis process is really important.
Along with the synthesis once I’m making my materials should I heat them for long or short periods of time?
So the processing - what I actually do to my material is also very important.
We’re looking at composition so what elements do I put in to make up my material?
How can I control the structure of the material?
Because structure is very important in determining the actual properties of the material
and then from the properties you get the actual performance. Okay?
If you’re making up a material how can you use your material?
What can you apply it to? And how well does it work?
So I’ve listed a couple of things that I work with.
Materials that I’m making up in my research group have a main focus on the environment.
So how can we keep the environment clean? How can we get energy in a clean and effective manner?
Summary:
Listen to Rachel describe the templating processes and following components:
Captions:
The process that my group is using is called a templating process,
and you are all very familiar with how to template.
You take a mould and then you use that to form the structure that you’re wanting as the end product.
So what I’ve depicted here in my schematic:
this is my mould the orangey colour here and these are large pores or holes in the actual mould.
And what I do is I do my chemistry inside the holes of the material, so I add a precursor molecule.
Here it’s titanium isoperoxide, this gets added in and it fills the holes of my porous structure.
Once it’s filled the holes I then do the chemistry,
so I add a bit of water to this, chemical reactions occur and I get a build up of,
in this case of titanium dioxide on the surface of the template.
And then I simply cook that template. I put it into an oven.
I heat it to about five hundred degrees Celsius and that burns out the actual template
and leaves me with a porous structure of an inorganic material,
here titanium dioxide, which is very similar to the original template that I started with.
And so what do I do if my materials basically,
I wanted to make titanium dioxide structures that are very porous.
I want lots of holes in my structure and so I take a template - here’s my film - it’s a very porous material.
And we’re looking at the micron scale okay so we’re not down to the nanometre level yet,
we’re looking at micro metres.
We take a film do our chemistry in the film and we produce a titanium dioxide structure
that is also a film okay and very porous in its final structuring.
And you’ll see why this is important in a minute. We can also take fibres.
So these are polymer fibres, organic material.
We coat this with titanium dioxide and we get tubular titanium dioxide materials as our final product.
Another is beads. You take polymer beads.
They’re porous on the outside surface as well as throughout the structure you do your chemistry inside that
and you get very porous titanium dioxide beads as your final product.
Summary:
As you watch the video, listen to what Rachel has to say about:
Captions:
Titanium dioxide is photoactive, that means that it is active under light.
If you shine a light onto a titanium dioxide nanocrystal what you get is a separation of an electron and a hole pair.
Okay. So in effect you’re exciting the titanium dioxide you get this free electron
free hole in the titanium dioxide and these can go out, interact at the surface,
and cause reactions to actually occur at the surface of the titanium dioxide crystals.
If you’re looking at the degradation of materials in water.
So if you’ve got pollutants in water you can use titanium dioxide
to actually degrade these by using these reactions
that are occurring at the surface of the titanium dioxide nanocrystal.
If you have a water solution and you’ve got lots of little particles in there once you’ve done your chemistry
the problem is how do I remove those little particles from the solution?
And that’s where my work becomes really important.
We make up films of titanium dioxide or particles of titanium dioxide that contain lots of little crystals
so that they have a high surface area, there’s a lot of surface still there.
And yet they’re bulky enough that you can handle them quite easily and remove them from solution.
Some of the reactions we look at: if we take a dirty water system
this particular example has got a carcinogenic pollutant in there.
It’s 2- chlorophenol.
And this is often found in the industrial waste waters of your chemical plants and some of your fabric plants.
If we add titanium dioxide to this beaker there’s oxygen present in the water
and we add some sunlight then we can actually degrade this down to CO2, water and a little bit of HCI.
And this is complete mineralisation, complete degradation of the pollutant to much less harmful materials.
Not only does it work in aqueous solution but it can be coated onto surfaces as well.
So here’s an example taken from Toto, a company in Japan,
where on the left hand side you see tiles that have been coated with titanium dioxide
on the right tiles that haven’t been coated with titanium dioxide.
If you leave them outside for a period of time dirt and grime comes and sticks on the ones that are not treated
whereas the ones that are treated remain clean. Okay?
So photo catalytic reactions are occurring on that surface and producing in effect a self cleaning surface.
And this works not only for dirt but also for bacteria.
If you have bacteria on a surface that has titanium dioxide on it
so long as that surface gets water and light shone on it,
it can actually destroy or break up the bacteria that’s placed on the surface.
And this hasn’t come out too clearly.
On the left-hand side again you’ve got the treated surface after thirty minutes of light being shone on it.
You’ve got a non-treated surface
and if you can see the little spots here this is bacteria such as your E.coli okay.
Within thirty minutes 99.9 % of the bacteria is completely destroyed okay.
And so in Japan this is really big they are using these tiles to actually make their medical wards okay.
The flooring in medical wards, their surgical wards also have these tiles on them.
Due to the fact that, one, they clean by themselves and two, they kill and destroy bacteria.
Summary:
Listen to Rachel as she talks about her work with titanium dioxide and think about:
Captions:
The last example I am going to show is photovoltaics, so here we are looking at solar energy.
Some examples shown here.
These are actually dye-sensitised solar cells. So cells that are being made here in Australia.
We have a company just outside of Canberra that makes up this specific cell and how does this cell work?
Again it’s composed of titanium dioxide. Surface area is really important. Here’s your titanium dioxide crystals.
It’s a porous structure and what you’re doing is your going to coat this porous structure with a dye
and it’s the dye that’s going to absorb the light.
So the more surface you have the more dye you can put down, the more dye you put down the more light
you can actually absorb and it's absorbing light that allows you then to get power out of the cell.
So we have a very porous titanium dioxide structure,
we have dye coated onto that structure and then we shine light onto the cell.
Shining light onto the cell you get again the excitation of the dye so you get this free electron being formed.
And that free electron can be injected into the titanium dioxide structure.
Once it’s in the titanium dioxide structure it can travel through.
Titanium dioxide is a semi-conductor so the electron can travel through the system
you harness the power as it travels through the load
and then you’ve got chemical reactions occurring in the solution of the cell
which in effect give that electron back to the original dye.
So it’s a completely cyclic process that allows just through the absorption of light the production of electricity.
And so within my group we’re working on how can we actually produce these porous structures
so we’ve got really high surface areas that we’re controlling the properties
and thereby enhancing the performance of these dye-sensitised solar cells.
Summary:
As you watch the video, listen to what Rachel has to say about her research and life:
Captions:
As I speak about my group, this is my research group at the University of Melbourne.
I have a very international group. I have people from Singapore, Malaysia, America,
and New Zealand as well as from Australia and China.
We have a lot people coming and going to work in the research group
and we have people working on things such as the dye-sensitised solar cells, photo catalysis,
I have a student working on bone like materials where we’ve got porous bone structuring materials
and we also have people working on the sequestration or removal of radio active elements from nuclear waste.
Apart from my research group I also I have my family and I put in a picture of them.
This time I have my husband here in the middle and my two daughters
and without their support it would be impossible, I think, to move forward in science.
It’s through their support and encouragement, that my children give me we have to have a better,
cleaner environment for the future, for the next generation of children and people coming through
and that’s what inspires me with my work. And, with that, I’d like to thank you all for your attention. Thank you.
Students: Applause
Music: Music