The Science Behind Our Self Cleaning Products
Of all the questions we get about our line of self-cleaning surfaces, the one we hear the most is “How do they work?”
The short answer is that our surfaces use nanocrystal technology to create a powerful oxidation reaction when exposed to any visible light.
A longer answer is that we bond microscopic mineral nanocrystals across our touchable surfaces, using the latest in material science. When natural or artificial light hits those mineral nanocrystals, the nanocrystals actively self-clean through a natural photocatalytic oxidation process.
The full answer is longer still and includes a lot of science. Here, we break it down.
Self Clean Self-Cleaning Surfaces are Photocatalytic
The term “photocatalysis” is comprised of two parts – “photo” referring to the use of light and “catalysis,” referring to the use of a substance to speed up a reaction rate. Photocatalysis is defined as the acceleration of a reaction by the presence of light and a catalyst. There are various materials that show photocatalytic capabilities, but Titanium Dioxide (TiO2) –– a material we use in our products –– has been the most widely studied photocatalyst over the past 40 years, not just because it works but also because it's safe (i.e., non-toxic).
How Does a Photocatalyst Work?
Upon absorbing energy from a light source, a photocatalyst material (like our self-cleaning surfaces) generates higher-energy electrons that fuel a process that results in the breakdown of toxic organic matter into carbon dioxide and water.
When light illuminates the surface, electrons are released and bind to oxygen (O2) to form superoxide anions (O2-), which are able to degrade organic material. The photocatalyst then becomes positively charged and removes single electrons from moisture in the air, creating hydroxyl radicals (OH*). Hydroxyl radicals are short-lived molecules that can also physically decompose organic contaminants into water and carbon dioxide. Superoxide anions and hydroxyl radicals are called reactive oxygen species (ROS). These ROS further react when exposed to oxygen and humidity leading to the formation of hydroperoxyl radicals (HO2). ROS react with organic material, such as proteins and polyunsaturated fatty acids, leading to physical degradation of the contaminant. These processes are energized by any type of visible light, including incandescent, fluorescent and LED.
Mechanical/Physical vs Chemical
A key distinction that needs to be made between smart materials like our self cleaning surfaces and other surface treatments and technologies is whether the cleaning activity is due to physical/mechanical actions or due to a substance or mixture of substances. In other words, our surfaces work by physical means (light and electricity) rather than a chemical substance that is generally toxic. The other main difference is with a catalytic process nothing is released from the surface. The technology is creating the cleaning action without sacrificing itself or releasing embedded toxins. A similar approach is used by ozone generators. They use electricity to split oxygen molecules. Self Clean works in a similar way but gets the charge from light rather than from an electrical outlet; it’s a green solar approach.
And speaking of green: Not only do our surfaces create the self-cleaning action through a catalytic process rather than releasing toxins, but TiO2 also has an exemption from toxicity tolerance because it is categorised as an inert ingredient.
If you’ve made it this far, we hope walking you through the science answered your most pressing questions.
If you have any questions, please feel free to send us an email or drop us a line.
We’d love to talk shop with you!