Photocatalytic Conversion of Plastic Waste: From Photodegradation to Photosynthesis

Abstract

Plastic waste remains a global challenge due to the massive amounts being produced without satisfactory treatment technologies for recycling and upcycling. Photocatalytic processes are emerging as green and promising approaches to upcycle plastics into value‐added products under mild conditions using sunlight as the energy source. In this review, the recent advances in plastic conversion through photocatalysis have been comprehensively summarized. Special emphasis is placed on the photocatalytic mechanism and the selective CC and CH bond transformations of plastics to access fuels, chemicals, and materials. Finally, the challenges and the perspectives on establishing a new paradigm toward a sustainable and circular plastic economy are also put forward.

Catalytic oxidation of polystyrene to aromatic oxygenates over a graphitic carbon nitride catalyst

“…Photocatalysis is considered as a green and promising technique. By utilizing energy of light, photocatalytic process can be achieved under mild conditions 13 , 19 . The different chemical processes of photocatalysis compared with thermal catalysis also make it possible to achieve unique reaction selectivity 14 , 19 , 20 .…”

“…(openloop recycling processes). In addition to the traditional thermochemical catalytic approaches, photo- [13][14][15] , electro- [16][17][18] catalytic approaches of upcycling plastic wastes have drawn wide attention. Photocatalysis is considered as a green and promising technique.…”

Plastic Waste Valorization by Leveraging Multidisciplinary Catalytic Technologies

“…Photocatalytic processes are considered as green and cheap techniques for plastic reclamation because of their mild conditions using sunlight or simulated light. , Conventional photodegradation has long been studied as an eco-friendly and viable way to convert end-of-life plastics into CO 2 and H 2 O . However, photodegradation may result in net carbon emission.…”

“…136,137 Conventional photodegradation has long been studied as an ecofriendly and viable way to convert end-of-life plastics into CO 2 and H 2 O. 136 However, photodegradation may result in net carbon emission. Alternatively, photoconversion of waste plastic to valuable products without carbon emission is highly desirable.…”

Trash to Treasure: Photoreforming of Plastic Waste into Commodity Chemicals and Hydrogen over MoS2-Tipped CdS Nanorods

“…Despite such sustained advances, the plastic substrates investigated in the previous reports are mainly concentrated on polyesters ( e.g ., PLA and PET). As a matter of fact, with the presence of alkali, these polar plastics with ester bonds are easily hydrolyzed into their constituent monomers that can be chemically valorized via photoreforming. − Compared with polyesters, polyolefin polymers dominated by C–C linkages, including polyethylene (PE), polypropylene (PP), and polystyrene (PS), account for a larger proportion in plastics (∼83–84%) but remain a huge challenge to recycle in an economic way owing to the robust C–C bond. − Current solutions ( i.e ., pyrolysis and gasification) to chemically upgrade PE are normally carried out under high temperatures (>500 °C), which requires a large amount of energy supply and increases the carbon footprint. − Therefore, a question has been raised as to whether it is possible to design a high-performance photocatalyst for photoreforming of plastics ranging from polyesters to polyolefins.…”