Titanium dioxide, better known as a key ingredient in white paint, is beginning to carve out an all-purpose spot for itself in the field of air pollution control. While not yet up to the ShamWow standard for range of applicability, this common substance could be on the verge of playing an even larger role in sustainability-related fields, as scientists at the University of Washington have unlocked the mechanism behind its strong reactive powers.
Smog-Eating Buildings, and More
Titanium dioxide has photocatalytic properties, meaning that sunlight sets off a reaction on the surface of its molecules.
Alcoa has already developed this property into a titanium-based coating that enables buildings to “eat” smog by converting airborne nitrogen oxide (a major contributor to smog and acid rain) to nitrates. A company called Pureti has been developing a similar concept for a surface treatment that could be applied to roads, to neutralize nitrogen oxide emissions from vehicles.
The sensitivity of titanium dioxide to airborne pollutants has also led to the development of a bomb detection device inspired by silkmoth antennae.
In addition to its pollution-fighting capabilities, titanium dioxide is being explored as a means of increasing the efficiency of solar energy conversion. Specifically, a solar cell enhanced with titanium dioxide would provide an emission-free way to produce hydrogen for use in fuel cells (check out MIT researcher Daniel Nocera’s “artificial leaf,” for example).
The Key to Titanium Dioxide
According to a long body of research into metal oxides like titanium dioxide, chemical reactions on the surface are comprised of a transfer of electrons, while the atoms themselves stay put.
The Washington research revealed that in some cases, the transfer can also include electrons coupled with protons.
As explained in a prepared statement by chemistry professor James Mayer, this discovery could lead to new technologies based on more efficient reactions:
“Research and manufacturing have grown up around models in which electrons moved but not atoms…In principle this is a path toward more efficient energy utilization.”
Beyond Titanium Dioxide
As a corollary to more energy efficient pathways, the electron-proton coupling could lead to the use of common, low-cost substances to produce energy from chemical reactions, helping to lower the cost of fuel cells and solar cells.
Titanium dioxide is not the only candidate in this regard. The Washington team observed the same phenomenon in another common substance, zinc oxide, which is already being studied for its potential in developing the next generation of low cost solar cells.
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