Scientists at Stanford University have developed an incredible tiny and inexpensive chip that is able to efficiently grab solar energy and kill bacteria minutes after being dropped into water.
Sunlight makes for an excellent disinfectant, thanks to the presence of UV. When water is left in a clear plastic bottle in direct sunlight for example, UV rays are able to kill living bacteria in the water within 48 hours. (Note this applies to bacteria only, not chemical contamination)
But as amazing as natural UV rays are, they are also inefficient, carrying only 4% of the sun’s total output. This small black chip however is able to harness the power of UV rays in a powerful way. When left in water, the tiny chip can effectively cleanse water of bacteria within 20 minutes.
Stanford University scientists explain that the chip is covered in nanoflakes of molybdenum disulphide, which is an inexpensive and easy to obtain material. The flakes act as a photocatalyst, so when struck with sunlight, they set of a chemical reaction in the water. In this instance, the Stanford scientists added copper to the mixture, in order to make a ‘reactive oxygen species’, which performs in a way similar to hydrogen peroxide, a common ingredient used in bleach.
Under an electron microscope, the surface of the chip looks something like a fingerprint with many closely spaced lines, which are called ‘nanoflakes’ of molybdenum. Maximizing their surface areas, nano-flakes on the surface of chip are arrange so that they stand on their edge.
This chip is so effective that when put in water, the scientists explain it is able to kill 99.99% of bacteria within 20 minutes. Although it has been tested on only three kinds of bacteria, the disinfectant it produces is expected to also work on other bacteria, as well as viruses, much like regular UV light. As noted above however, it does not however claim to work with chemical contamination.
Simple and inexpensive, this material has great potential for application in areas of the world that struggle with a lack of access to clean drinking water free of harmful bacteria.