Upcycling of Plastic Waste Using Photo-, Electro-, and Photoelectrocatalytic Approaches: A Way toward Circular Economy

Rapid industrialization and development have led to a tremendous increase in the use of various types of plastic commodities in daily life. For the past several years, plastic pollution has become a global issue, posing a serious threat to mankind. The primary issue with increasing plastic pollution is the lack of proper management which has created huge havoc in the environment. From the initial phase of plastic waste management, plastic waste has been discarded, recycled, downcycled, or dumped into landfills in a large proportion, causing extreme damage to the ecosystem. Conventionally, plastic waste is treated via thermal processes such as pyrolysis or incineration plants which require a large amount of capital and, therefore, harms the aim of circular economy. Chemical upcycling is gaining large attention as a high-potential catalytic strategy to convert waste plastics, such as polyethylene terephthalate, polyethylene, polystyrene, etc. to various fuels, functionalized polymers, and other value-added chemicals having a direct impact on affordability and viability. In this review, we have focused on the use of photocatalysis, electrocatalysis, and photoelectrocatalysis as effective and efficient plastic upcycling technologies. These approaches can lower the dependence on nonrenewable resources and, therefore, are more environmentally friendly in contrast to the conventional approaches. This review elaborately discusses the pros and cons of the conventional approaches and provides a detailed overview of the potential of renewable energy-driven approaches for the conversion of plastic wastes to valuable fuels and commodity chemicals, along with the challenges and future directions of this emerging approach for plastic waste treatment.