【Frontiers in HaiChuan Chemical Technology】Breakthrough achieved in photocatalytic plastic decomposition technology at the Institute of Metal Research, Chinese Academy of Sciences

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Breakthrough in photocatalytic plastic decomposition technology: Recently, researchers from institutions such as the Institute of Metal Research, Chinese Academy of Sciences, have developed a floating titanium dioxide material. This material can decompose plastics when exposed to light; without the need for pretreatment of the plastics with acid or alkali solutions, its efficiency in breaking down common plastics such as plastic bags and plastic wrap is dozens to hundreds of times higher than that of traditional materials, setting a new record for plastic decomposition efficiency under neutral conditions. The relevant findings were published in Nature Communications. 　　Currently, the total amount of plastic waste worldwide has reached 6.4 billion tons, posing a serious threat to environmental safety and human health. How to deal with this waste plastic has become a global challenge. Against this background, photocatalytic plastic decomposition technology has attracted attention. This technology can convert waste plastics into useful chemical raw materials by using light to irradiate semiconductor photocatalytic materials. 　　Titanium dioxide is a commonly used semiconductor photocatalytic material that can generate hydroxyl radicals capable of decomposing plastics under light exposure. These hydroxyl radicals act like “molecular scissors,” capable of cutting the molecular chains of plastics. However, hydroxyl radicals have significant drawbacks: their lifespan is only on the order of one billionth of a second, and their effective range is limited to 10 to 100 nanometers. Short-lived free radicals have difficulty reaching the surface of plastic products effectively. Therefore, people have to first corrode the plastic using strong acid or strong alkali solutions, but this pretreatment step accounts for 85% of the total cost of the degradation process. 　　In this study, researchers broke away from conventional approaches by coating titanium dioxide with a \"waterproof armor\" to enable it to float on the water’s surface. Compared to traditional titanium dioxide, floating titanium dioxide has two new functions. First, it enables direct contact between sunlight, oxygen, photocatalytic materials, and plastic, breaking through the barrier that previously existed between photocatalytic materials and plastic. Second, it can make use of superoxide radicals with a longer lifespan – up to 1 millisecond – which allows for the complete disruption of the carbon chains in plastic molecules.