Plastic pollutants: From wastes to fuels and high-value chemicals

Every year, a large number of plastic products are used extensively and discarded worldwide, causing severe plastic pollution that contaminates the soil, air, and water supplies. While solar energy can help in the sustainable degradation of plastics, the process takes time and releases harmful chemicals that contaminate the food and water cycles. This review examines existing conventional methods and emerging processes for solar-driven catalytic plastic degradation. Conventional methods, such as pyrolysis, catalytic cracking, hydrogenolysis, and electrocatalysis, are discussed, focusing on the requirement for a more sustainable approach. In particular, this review highlights how the catalytic potential can be enhanced by activating chemical bonds to yield value-added products by photocatalytic upcycling under moderate circumstances. Photocatalytic upcycling, as a sustainable approach, has been explored for hydrogen production and the production of value-added chemicals using the waste plastic substrate, signifying “treasure from trash”. The key obstacles to the uptake and expansion of these technologies are identified, along with recommendations for future research directions to improve the effectiveness of upcycling techniques.