Researchers at the ARC Centre of Excellence in Exciton Science have demonstrated a quick, efficient way for solar energy to break down toxic dyes used in the textile industry.
Waste products from textile mills present a major threat to ecosystems, biodiversity and water quality, and place a major strain on treatment facilities.
Scientists have been exploring the potential to use the sun to address this challenge, by taking advantage of a process called photocatalysis.
Unlike in solar panels, where parts of the light spectrum are captured and converted in electricity, photocatalysis transforms the sunlight directly into chemical energy, causing chemical reactions in liquids.
This still requires the use of the semiconductor materials, but instead of being located in solar panels, the semiconductors must be available in a liquid particle form, in this case one that’s able to break down toxic dyes in textile industry wastewater.
For the approach to be viable at scale, these semiconductor materials must be easy and cheap to make, and recyclable, so that they can be used in multiple treatment sequences. It is also important for the semiconductor materials to absorb the right portions of the light spectrum.
Bismuth sulfide is one promising candidate, and has been paired with photosensitiser metals such as gold, silver and platinum, but many experiments so far have involved too many steps to be practical, included toxic materials of their own, and were not efficient enough at breaking down the pollutants.
Now, Exciton Science researchers based at The University of Melbourne, together with collaborators from the International Academy of Optoelectronics at Zhaoqing, have demonstrated a simple way of creating useful photocatalyst nanostructures made from a combination of bismuth sulfide and gold nanoparticles.
This combination, which has the key advantage of being simple to make and recyclable, was shown to deliver a high level of stable photocatalytic activity, successfully breaking down test pollutants in a simulation of the real conditions that would occur in sunlight.
The researchers are hopeful that by successfully demonstrating this relatively simple approach, a path may open up to establishing a similar mechanism at the scale necessary for commercial applications.
Their results have been published in the journal catalysts and are available here: https://www.mdpi.com/2073-4344/11/3/355