(music)
I want to live in a world where I don't have to worry
if whether or not there will be any planet left
for our future generations
If we look at the timeline of Earth no other species
has modified this landscape the way we have done it
and that is both very exciting and worrisome.
We have achieved the most amazing things as humankind
We went to the moon. We can orbit around the Earth.
We invented computers and created the internet.
And we made all this possible
because we are able to understand and manipulate matter
at its most fundamental forms.
But it all has come at a cost.
Currently, in the U.S. we obtain most of our energy from burning fossil fuels
We burn oil, coal, and natural gas to produce electricity
to power our houses and our devices.
But by doing this we also produce a molecule called carbon dioxide.
We already know that when carbon dioxide gets emitted to the air in excess
it causes global warming
but we cannot obtain any energy from CO2
so we just release it, because it is a waste for us.
and it is also not a toxic chemical by itself
We can breathe it. It actually smells nice and, in fact the smell of CO2,
can be described as freshly baked bread.
I learned about CO2 when I was in elementary school back in Mexico
and I was always intrigued by a molecule like this
I was always a very curious boy and luckily I was the son of an educator.
My mother taught elementary school so she let me unleash all of my scientific curiosities
She encouraged me to read, so I read about CO2 and about dinosaurs and
about Carl Sagan and that little pale blue dot that is our planet.
I was also a Boy Scout and you may think that I was a nerd
and you may think right, because being a Boy Scout in Mexico was really fun
I learned about rocks. I learned about camping. I learned that we humans
have a very special relationship with nature.
And that in the words of Robert Baden-Powell,
we must try and leave this world a little better than we found it.
And those words have stayed in my mind ever since I heard them for the first time
when I was 12 because I understood that it is our duty to protect
a little pale blue dot because it is our home .
It was also in school when I learned about photosynthesis
and I hope you like my semi-technical drawing of photosynthesis,
which is the natural process in which plants take water, CO2, and use sunlight
to produce oxygen.
and to remove the co2 from the air.
We animals breathe it out
and plants take it in, which gives a balance that maintains the temperature
of the atmosphere steady, making this planet habitable.
Unfortunately we release so much CO2 from burning fossil fuels
that we've altered this balance
and right now, all the plants on Earth are just not enough to restore the levels of CO2
to restore this balance.
So we created global warming and we are already seeing
all the changes that have been predicted at a global scale
like hurricanes getting stronger every year,
or the disappearance of beaches
and islands from the rise of the sea levels
or the death of very important animals for our food production
like starfish or bees or coral reefs
and I can go on and on but I'm here because I want to give an inspiring talk
not a depressing one.
Now we have made similar mistakes in the past. We damaged the ozone layer so much
that it also threatened our existence on Earth.
The difference is that back then it was visible.
The big hole over Antarctica.
So we got really worried and we did something about it.
We created the Montreal Protocol which has been the
most successful international agreement that has helped reducing the thinning of the ozone layer.
But with CO2, it's more complex.
We have the Paris Agreement but we don't see a hole in the atmosphere
and we need to produce electricity.
I remember growing up seeing chimneys with smoke coming out all day long
and thinking, "Is there anything that we can put on top of those chimneys to make
those fumes less harmful? Is there anything that we could do to turn all that waste
into something useful? Is there anything that I could do?"
So I became a scientist.
and I learned that there is something we can do to fight
the global warming threat. That we can develop new, exciting science
that can help us to remove the CO2 from the air
then we can make artificial systems that
can emulate the natural processes, so we can adapt to global warming and fight it.
I learned that we humans are capable of recreating photosynthesis in the lab
with materials that are entirely made by us.
When I became an independent researcher
I learned that I am not the first one to be concerned with this scientific challenge
that there is an army of very smart and very talented
people that are just as worried as I am
and each of these scientists, technologists, and engineers
has their very own unique and creative way to pursue
artificial photosynthesis. And that I had to learn from them,
"to see it on the shoulders of these giants," as Isaac Newton once said.
In order to achieve artificial photosynthesis,
we first need to understand how the natural process occurs
which happens in two steps in different parts of the plant at different times.
The first step is called "water splitting," in which a plant picks off a particle of light
which is pure energy
and uses that energy to rip apart two molecules of water
it produces oxygen and it stores all
that energy in chemical bonds
as chemical energy.
Now to do this, most plants utilize red color
and it's gonna sound weird but that is why we see them green.
Green is a complementary color of red and we see the complementary colors.
So what we want to do is to use more colors of the light that comes from the Sun,
these are the different types of light that come from the Sun
a little bit more than half is visible light
which are all the colors of the rainbow combined together
and is the energy that we want to use for artificial photosynthesis.
Three percent, about three percent, is ultraviolet light, which has high energy
and is very damaging for us and most of it it gets filtered by the ozone layer.
The rest is infrared light, which is heat that comes from the Sun
and it is the heat the CO2 gets trapped in the atmosphere.
The second step it's called, "carbon fixation"
in which the plant uses that chemical energy that it obtained from
water splitting to trap a molecule of CO2 and to embed it as part of its structure.
So this process, it's very inefficient to store energy. iI's just about 2%
but it's just enough to make plants live and to populate the Earth
and to remove the CO2 from the Earth.
Now what we want to achieve is a material in which we can
combine both steps as a single process that we call "direct carbon reduction,"
in which a material will pick up a particle of light and transfer all that energy to
a molecule of CO2. And then that CO2 can get transformed in another chemical that has
more energy.
That is a fuel that we can burn.
A solar fuel because it was created with energy that came directly from the Sun.
Now there are other many
artificial photosynthesis materials that are very efficient.
The challenge is that you are required to use very rare and very expensive elements
like platinum.
Platinum is very rare and one pound of platinum costs
more than $10,000, which okay, I guess it's okay for wedding rings or tennis
bracelets, but not to do artificial photosynthesis at the large industrial scale.
So what we try to do in my lab is we try to make materials that are
composed of elements that are more abundant, that are much less expensive.
And I'll take our inspiration on white paint
and if there is any artist or a painter in the room
you will recognize this color. It's called titanium white.
The pigment in this color -- it's a crystal called titanium dioxide
and it is a material that can perform artificial
photosynthesis through direct carbon reduction.
Now the challenge is that to do this process it requires ultraviolet light
which is only 3% of what comes from the sun.
And it's also a very slow process
so it is also not economically viable to use this material at a large scale.
However, it's a very inexpensive element.
It's very abundant. One pound of titanium dioxide costs only seven cents
and it is literally dirt cheap.
Especially if we
compare it to platinum.
So what we do in my lab, my students and I will put together
titanium with molecules that are able to capture
different colors of the light.
And we assemble them into this type of materials that we call frameworks.
They are kind of like tinker toys but with molecules
that form these beautiful three-dimensional architectures
that has a lot of holes
so then they CO2 can pass through really fast.
In reality the material looks like this:
it's a yellow powder and it is yellow because it absorbs blue light
and yellow is a complementary color of blue.
So we put it in this little bottle
we add some chemicals,
we bubble it with CO2 and we put it in this photo reactor
the looks like a tanning bed, but it's made out of blue LEDs.
We use LEDs because they're very accessible
and they simulate very well different colors
of the light.
Alright, so as a molecule of CO2 is passing through the framework
the material picks up a particle of light and transfers all that
energy to the CO2 and that the CO2 gets turned into a solar fuel
and it leaves the material
and what we were able to see in our first study
is that we can do this at rates much faster than titanium dioxide
so it is very promising,
And we know that we can implement all these materials in current technology.
So modern power plants, after they burn fuel and produce electricity
they had to process all the gases
because some of them are very polluting
so as CO2 also gets purified at the very end
gets either released to the atmosphere
or pumped into the ground.
So it is here where it could implement our artificial photosynthesis systems
because we can turn all that CO2 back into a solar fuel
so they could feed it it back into the plant
and we can achieve two things
First, we increase the efficiency of the plant
because we can produce more electricity
so we can actually make a profit using artificial photosynthesis
and second that since we are reducing our own carbon we are producing
electricity without emitting it
achieving a carbon neutral process
so we can use artificial photosynthesis to produce electricity
in a carbon neutral process.
That sounds so cool.
(laughter)
But, of course, our materials are not perfect.
There is a lot of application that we have to do.
We want to be able to use more colors of the light.
We want to make this a much faster rate and have higher efficiencies of photosynthesis
So there are a lot of experiments to do
And we're really excited about it
but we learned a couple of things
We learned how the machinery of how artificial photosynthesis materials work,
so we know how to make them better.
We know that we can create new science that can help us to adapt to climate change.
And then we can fight it
and then we can make a profit.
We learned also that we can go beyond photosynthesis
that we can make frameworks
with all the elements of the periodic table.
And we can use them to explore new properties
to discover new unknown phenomena.
That we can make atoms and molecules
organized exactly the way we want them.
And I know that I am already nerding out really hard in here
but this is the kind of things that we chemists dream about.
Of course I cannot do any of these alone.
I need to rely on the younger generation of people
so we need to make science and technology more attractive.
So what we do is that we bring students to our labs.
We do science demonstrations
like we do every year in our STEM day.
We go to the schools and we organize
activities like the National Crystal Growing Competition that we do every year
so the students can do the experiments themselves,
so they can understand science and see how fascinating it is.
We also need to make science and technology more diverse
so we work with the Alliance for Diversity in Science and Engineering
a national nonprofit organization that brings together
students and faculty from all backgrounds
because diversity enriches us
and it is what makes America great.
We need to encourage our children to be curious
to ask questions
so they can become the scientists and the engineers
of the future.
Like my students in my research groups,
They are the ones that are mixing the chemicals, making the materials, and testing the photosynthesis.
They are the ones who are going to make the new scientific discovery,
the new technological advancement, so that with them together
we can solve this problem of global warming.
Because guess what? We need their help.
Thank you very much.
(applause)