Asymmetric Atomic Pt–B Dual-Site Catalyst for Efficient Photoreforming of Waste Polylactic Acid Plastics in Seawater

Waste plastic has imposed significant burdens on marine ecosystems. Converting plastic into high-value products via photocatalysis is an emerging and promising approach, but its low activity and product selectivity pose great challenges. Herein, we report a carbon nitride-anchored atomically dispersed Pt–B dual-site catalyst (Pt SA/BCN100) for the photoreforming of polylactic acid (PLA) into high-value chemicals and H₂ in seawater. Experiments and DFT calculations reveal that significantly enhanced charge transfer occurs between the Pt site and the B site, and the hole-rich B site can selectively trigger the activation and cleavage of the C–H and C–C bonds of PLA to form acetic acid (AA), while the electron-rich Pt site drives the reduction of H protons to H₂. As a result, Pt SA/BCN100 exhibits a high H₂ evolution rate of 993 μmol g_catal^–1 h^–1 and an AA production rate of 300 μmol g_catal^–1 h^–1 with a selectivity of over 98%. We also demonstrate the direct photoreforming of g-scale real-world PLA wastes and low concentrations of PLA microplastics in natural seawater. Techno-economic analysis and environmental assessment show that this catalytic system can significantly reduce carbon emissions and has potential commercial value.