Photocatalytic production of high-value-added fuels from biodegradable PBAT by Nb2O5/GCN heterojunction catalyst: Performance and mechanism

Photocatalysis holds great promise for the conversion of plastic waste into valuable chemicals. However, the conversion efficiency is constrained by the poor carriers' separation efficiency over the single component photocatalyst. Herein, we synthesized a novel type Ⅱ Nb₂O₅/GCN heterojunction to investigate its efficiency in the photocatalytic upcycling of polybutylene adipate/terephthalate (PBAT) microplastics (MPs) into acids and alcohols under visible light irradiation (100 mW/cm2). The findings indicate that the charge transfer within the type Ⅱ Nb₂O₅/GCN occurs from the conduction band of GCN to the conduction band of Nb₂O₅, thereby enhancing the separation efficiency of carriers Notably, the rates of ethanol and acetic acid generation from 1.5 mg/mL PBAT MPs treated with the 60 %Nb₂O₅/GCN photocatalyst were 21.8-fold and 1.8-fold higher, respectively, compared to those by Nb₂O₅ alone. Density functional theory calculations demonstrate that the hydroxyl radicals (^•OH) produced by the Nb₂O₅/GCN heterojunction cleaves the ester bond (OC=O) of PBAT MP into the monomer. These monomers are subsequently converted into acids and alcohols through various reactions, including CC bond cleavage, hydrodeoxygenation, and CC bond coupling. This study highlights the effectiveness of heterojunction photocatalyst in converting PBAT MPs into valuable chemicals, thus significantly promoting advancements in bioplastics recycling.