From a straw to a car, plastic products have been integrated into every aspect of human life. So far, nearly 10 billion tons of plastic have been produced globally, with only about 10% being recycled, and the remaining amount being burned or discarded in landfills or natural environments. Due to the strong chemical inertness of plastics themselves, it takes at least hundreds of years to fully degrade under natural conditions, leading to the continuous accumulation of waste plastics in the natural environment, posing a threat to human health and the ecological environment. The traditional plastic landfill method occupies a large amount of land resources, causes serious resource waste, and causes secondary pollution to soil, water resources, atmosphere, etc. Every year, 10 million tons of discarded plastic flow into the ocean worldwide, posing a fatal threat to marine life. In addition, the plastic product industry consumes 8% of the world's total petroleum throughout its entire lifecycle. By 2050, the plastic manufacturing industry is expected to consume about 20% of the world's petroleum resources, and a large amount of discarded plastic also causes great waste of resources. Therefore, the recycling and utilization of plastics is urgent.
At present, the recycling of waste plastics mainly relies on physical recycling, but physical recycling has shortcomings such as limited types of plastics to be treated, incomplete treatment, low utilization rate, and low added value. At the same time, due to technical limitations, the quality of recycled plastics deteriorates and can only be degraded for use, ultimately still being discarded. This method is called degraded recycling. In contrast, the chemical recovery method conducts chain breaking reactions under the action of chemical or biological enzyme catalysts, depolymerizing waste plastic polymers into monomers. These monomeric small molecules can be used as raw materials for the preparation of other chemicals, and can also be recycled and re polymerized into plastics, providing groundbreaking solutions for the recycling of waste plastics. However, current chemical recovery is mainly based on thermal catalysis, which usually requires a large amount of thermal energy consumption, resulting in serious carbon emissions and the release of various toxic and harmful gases. Therefore, there is an urgent need to develop new and sustainable chemical recycling strategies for waste plastics.
Recently, electrochemical catalysis technology has gradually become a research hotspot in the fields of nanomaterials and energy chemistry. Compared to traditional thermal catalysis methods, electrocatalysis has the following characteristics: (1) active species can be generated in situ on the electrode through electron gain and loss, without the need for additional redox reagents; (2) The reaction can be carried out at room temperature and pressure under mild conditions with low equipment requirements and easy catalyst recovery; (3) Adjusting the electrode potential can control the Product selectivity and reaction rate, and reduce or avoid the occurrence of side reactions; (4) Electric energy can be converted from green renewable energy such as solar energy, hydropower, wind energy, tidal energy, etc., which conforms to the concept of sustainable development. Therefore, the electric catalytic reforming technology driven by renewable electricity is one of the ideal schemes to realize the high value utilization of waste plastics.
Recently, researchers from the Institute of Physical and Chemical Technology of the Chinese Academy of Sciences proposed the strategy of upgrading and recycling waste plastics by electro catalysis. Taking polyethylene terephthalate (PET) as an example, through electric reforming technology and water as a medium, PET can be converted and upgraded to high value-added glycolic acid and high-purity hydrogen, providing a new way for the sustainable and high-value utilization of waste PET plastics.
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