For some time now, we've been hearing about the benefits of drying our laundry outside on the clothesline. We save money and energy by not running the dryer, the sunlight kills germs, and we don't run the risk of generating harmful dryer emissions. In the future, however, we might also end up washing our clothes by hanging them outside - scientists in China have successfully used sunlight to remove orange dye stains from cotton fabric, that was treated with a special coating.

Mingce Long and Deyong Wu created the coating, which combines titanium dioxide and nitrogen. When exposed to sunlight, dirt on fabric treated with the coating breaks down, and microbes die. While the coating in its basic form is effective, it was found that it does an even better job at dispersing dye coloration when silver and iodine nanoparticles are added. Additionally, it is able to remain intact and active after washing and drying.

Although light-activated self-cleaning fabrics have been created previously, all of those required concentrated ultraviolet light, as opposed to natural sunlight.

Should the coating eventually be commercialized, however, there are doubtless many people who would want nothing to do with it. Although titanium dioxide is now an active ingredient in products such as sunscreen, cosmetics and paint, studies have shown that it can cause genetic damage in mice and brain damage in fish. This has led to concerns over the effect that it could have on humans, and the environment.

A paper on the coating was recently published in the journal ACS Applied Materials & Interfaces.