Catalytic Upgrading of Plastic Wastes into High-Value Carbon Nanomaterials: Synthesis and Applications

The surge in waste plastics has placed a serious burden on the global ecosystem. Traditional recycling methods are insufficient to handle the growing volume of plastic waste, highlighting the urgent demand for innovative recycling technologies. Transforming plastics into high-value carbon nanomaterials is a simple and efficient resource recovery strategy, especially effective for handling mixed or hard-to-separate plastic waste. This method not only simplifies the sorting of discarded plastics but also offers significant advantages in recovery efficiency and processing convenience. This review systematically summarized various technologies for converting plastics into carbon nanomaterials, focusing on the catalytic mechanisms of different conversion methods. We also analyzed how various catalysts, catalytic temperatures, and metal–support interactions affect the yield and quality of carbon nanomaterials. Additionally, the potential applications of carbon nanomaterials in environmental remediation, energy storage, and catalysis are also evaluated. The ongoing challenges and future research directions in this field are critically discussed, which will ultimately facilitate more effective resource recovery from plastics and contribute to the realization of a circular economy. We believe that this review will inspire more creativity in designing such win–win reaction systems to realize a “waste treat waste” concept.