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

Plastic valorization presents a significantly untapped opportunity to address environmental issues while creating the necessary economic push for a circular carbon economy. Compared with the conventional routes for processing plastics (e.g., pyrolysis and gasification), a photoreforming strategy, namely, photocatalytic plastic oxidation paired with water splitting, aims to achieve plastic valorization into commodity chemicals under mild conditions while offering hydrogen fuels. Here, we implement MoS2-tipped CdS nanorod photocatalysts in an aqueous medium to reform pretreated plastics that range from polyesters (e.g., polylactic acid (PLA) and polyethylene terephthalate (PET)) to polyolefins (e.g., polyethylene (PE)). The architecture of MoS2/CdS takes advantage of the anisotropic morphology and rapid charge transfer features of nanorods, by collecting the electrons at the MoS2 tip for hydrogen evolution and utilizing the entire sidewall of CdS nanorods with rich holes toward plastic oxidation. It is shown that continuous H-2 can be evolved from photoreforming of PLA, PET (commercial PET granules and real-world PET bottles), and PE, while these plastic substrates are accordingly converted into a series of valuable chemicals. This work provides an effective way to harness solar energy to realize the transformation of trash (plastics) to treasure (gaseous/liquid chemicals).

Automated summary

Photocatalytic oxidation combined with water splitting offers a mild and effective strategy to valorize plastic waste into valuable chemicals and hydrogen fuels. In this study, MoS2-tipped CdS nanorods are used as photocatalysts to reform various plastics into valuable chemicals, while continuously producing hydrogen gas. This research provides a promising approach to transform plastic waste using solar energy.