Posted on March 25, 2013 12:04 pm

Generate Hydrogen- Produce Clean Water - Even Provide Energy

Multi-Purpose Wonder Can Generate
Hydrogen, Produce Clean Water and Even Provide Energy

Mar. 23, 2013 — A new
wonder material can generate hydrogen, produce clean water and
even create energy.

Science fiction? Hardly, and there’s more — It can also
desalinate water, be used as flexible water filtration
membranes, help recover energy from desalination waste brine, be
made into flexible solar cells and can also double the lifespan
of lithium ion batteries. With its superior bacteria-killing
capabilities, it can also be used to develop a new type of
antibacterial bandage.

Scientists at Nanyang Technological
University (NTU) in Singapore, led by Associate Professor Darren
Sun have succeeded in developing a single, revolutionary
nanomaterial that can do all the above and at very low cost
compared to existing technology.

This breakthrough which has taken Prof Sun five years to
develop is dubbed the Multi-use Titanium Dioxide (TiO2).
It is formed by turning titanium dioxide crystals into patented
nanofibres, which can then be easily fabricated into patented
flexible filter membranes which include a combination of carbon,
copper, zinc or tin, depending on the specific end product
needed.

Titanium dioxide is a cheap and abundant material, which has
been scientifically proven to have the ability to accelerate a
chemical reaction (photocatalytic) and is also able to bond
easily with water (hydrophilic).

More than 70 scientific papers on Prof Sun’s work in titanium
dioxide has been published in the last five years, the latest
being papers published in Water Research, Energy
and Environmental Science,
and Journal of Materials
Chemistry.

Prof Sun, 52, from NTU’s School of Civil and
Environmental Engineering, said such a low-cost and easily
produced nanomaterialis expected to have immense potential to
help tackle ongoing global challenges in energy and
environmental issues.

With the world’s population expected to hit 8.3 billion by
2030, there will be a massive increase in the global demand for
energy and food by 50 per cent and 30 per cent for drinking
water (Population Institute report, titled 2030:
The "Perfect Storm" Scenario)
.

"While there is no single silver bullet to solving two of the
world’s biggest challenges: cheap renewable energy and an
abundant supply of clean water; our single multi-use membrane
comes close, with its titanium dioxide nanoparticles being a key
catalyst in discovering such solutions," Prof Sun said. "With
our unique nanomaterial, we hope to be able to help convert
today’s waste into tomorrow’s resources, such as clean water and
energy."

Prof Sun’s multi-use titanium dioxide can:

  1. concurrently produce both hydrogen and clean water when
    exposed to sunlight
  2. be made into a low-cost flexible filtration membrane
    that is anti-fouling
  3. desalinate water as a high flux forward osmosis membrane
  4. recover energy from waste desalination brine and
    wastewater
  5. be made into a low-cost flexible solar cell to generate
    electricity
  6. doubles battery life when used as anode in lithium ion
    battery
  7. kill harmful microbial, leading to new antibacterial
    bandages

How the wonder material was found

Prof Sun had initially used titanium dioxide with iron oxide to make
anti-bacterial water filtration membranes to solve biofouling — bacterial
growth which clogs up the pores of membranes, obstructing water flow.

While developing the membrane, Prof Sun’s team also discovered that it could act
as a photocatalyst, turning wastewater into hydrogen and oxygen under sunlight
while still producing clean water. Such a water-splitting effect is usually
caused by Platinum, a precious metal that is both expensive and rare.

"With such a discovery, it is possible to concurrently treat wastewater and yet
have a much cheaper option of storing solar energy in the form of hydrogen so
that it can be available any time, day or night, regardless of whether the sun
is shining or not, which makes it truly a source of clean fuel," said Prof Sun.

"As of now, we are achieving a very high efficiency of about three times more
than if we had used platinum, but at a much lower cost, allowing for cheap
hydrogen production. In addition, we can concurrently produce clean water for
close-to-zero energy cost, which may change our current water reclamation system
over the world for future liveable cities."

Hydrogen is a clean fuel which can be used for automotive fuel-cells or in power
plants to generate electricity.

Producing hydrogen and clean water

This discovery, which was published recently in the academic journal, Water
Research, showed that a small amount of nanomaterial (0.5 grams of titanium
dioxide nanofibres treated with copper oxide), can generate 1.53 millilitre of
hydrogen in an hour when immersed in one litre of wastewater. This amount of
hydrogen produced is three times more than when Platinum is used in the same
situation.

Depending on the type of wastewater, the amount of hydrogen generated can be as
much as 200 millilitres in an hour. Also to increase hydrogen production, more
nanomaterial can be used in larger amounts of wastewater.

Producing low-cost flexible forward osmosis membranes

Not only can titanium dioxide particles help split water, it can also make water
filter membranes hydrophilic — allowing water to flow through it easily, while
rejecting foreign contaminants, including those of salt, making it perfect for
desalinating water using forward osmosis. Thus a new super high flux (flow rate)
forward osmosis membrane is developed.

This discovery was published recently in last month’s journal of Energy and
Environmental Science. This is the first such report of TiO2 nanofibres and
particles used in forward osmosis membrane system for clean water production and
energy generation.

Producing new antibacterial bandages

With its anti-microbial properties and low cost, the membrane can also be used
to make breathable anti-bacterial bandages, which would not only prevent
infections and tackle infection at open wounds, but also promote healing by
allowing oxygen to permeate through the plaster.

The membrane’s material properties are also similar to polymers used to make
plastic bandages currently sold on the market.

Producing low-cost flexible solar cells

Prof Sun’s research projects have shown out that when treated with other
materials or made into another form such as crystals, titanium dioxide can have
other uses, such as in solar cells.

By making a black titanium dioxide polycrystalline sheet, Prof Sun’s team was
able to make a flexible solar-cell which can generate electricity from the sun’s
rays.

Producing longer lasting lithium ion batteries

Concurrently, Prof Sun has another team working on developing the black titanium
dioxide nanomaterial to be used in Lithium ion batteries commonly used in
electronic devices.

Preliminary results from thin coin-like lithium ion batteries, have shown that
when titanium dioxide sphere-like nanoparticles modified with carbon are used as
the anode (negative pole), it can double the capacity of the battery. This gives
such batteries a much longer lifespan before it is fully drained. The results
were featured in the Journal of Materials Chemistry on its cover page last year.

Next step — commercialisation

Prof Sun and his team of 20, which includes 6 undergraduates, 10 PhD students
and 4 researchers, are now working to further develop the material while
concurrently spinning off a start-up company to commercialise the product.

They are also looking to collaborate with commercial partners to speed up the
commercialisation process.