Catalytic carbon and hydrogen cycles in plastics chemistry

The soaring demands, production, and disposal of plastics have caused a great burden on the environment. Chemical degradation and catalytic transformation techniques are capable of decomposing or converting plastics into value-added chemicals, fuels, and functional nanocarbons. These techniques include thermal treatments, advanced oxidation, photocatalysis, electrocatalysis, and solvolysis. Understanding the transformation routes and destinations of the carbon and hydrogen elements in plastics is important for the development of advanced techniques to achieve plastic circular economy. To this end, we present an overview of the recent advances in carbon and hydrogen circulations by catalytic technologies in plastic chemistry. Insights will be provided to achieve material and economic sustainability via plastic recycling/upgrading toward a closed loop across energy, chemistry, and environmental sectors. Plastic pollution has attracted increasing attention from society and the research community. Various methods have been developed to recycle/upcycle plastic wastes in a more economic and environmentally friendly way. However, carbon and hydrogen sources in plastics usually end up in the environment and cannot be reused. Herein, we firstly introduce the fate of plastics from manufacture to traditional plastics treatment and summarize the product distributions and advances of different novel plastic treatments. This review discusses the upcycling routes of carbon/hydrogen after different advanced treatments and the potential of each technology to achieve circular economy. The current challenges and the future opportunities to form a closed loop of plastic carbon/hydrogen are also provided, which will help to realize a carbon-neutral society in the future. The soaring demands, production, and disposal of plastics have caused a great burden on the environment. Chemical degradation and catalytic transformation techniques are capable of decomposing or converting plastics into value-added chemicals, fuels, and functional nanocarbons. These techniques include thermal treatments, advanced oxidation, photocatalysis, electrocatalysis, and solvolysis. Understanding the transformation routes and destinations of the carbon and hydrogen elements in plastics is important for the development of advanced techniques to achieve plastic circular economy. To this end, we present an overview of the recent advances in carbon and hydrogen circulations by catalytic technologies in plastic chemistry. Insights will be provided to achieve material and economic sustainability via plastic recycling/upgrading toward a closed loop across energy, chemistry, and environmental sectors.