Synergistic polarization field enhancement and orbital engineering in Ti-doped KNbO3 for simulated solar irradiation upcycling of PBAT plastics

Ti doping intensifies the lattice asymmetry of KNbO 3 , resulting in a stronger polarization field. • Ti 3d orbitals hybridize into the CB of KNbO 3 , boosting photoelectron reduction ability. • Waste PBAT is selectively converted to high-value terephthalic acid via photocatalysis. Photocatalytic plastic upcycling offers a sustainable route to combat plastic pollution, yet its efficiency is severely bottlenecked by rapid charge recombination. Herein, B-site Ti-doped KNbO 3 ferroelectric perovskites were engineered for the selective conversion of PBAT into high-value terephthalic acid (PTA) monomers. Comprehensive characterizations and density functional theory (DFT) calculations reveal that the disparities in ionic radius and electronic configuration between Ti 4+ and Nb 5+ induce a dual-functional modification of KNbO 3 . Structurally, Ti incorporation intensifies the local lattice asymmetry of KNbO 3 and amplifies the off-center spatial displacement of charge centers, thereby reinforcing the intrinsic bulk polarization field to accelerate the separation of photogenerated charges. Electronically, the hybridization of Ti 3d orbitals elevates the conduction band bottom, boosting the reduction power of photogenerated electrons to drive rapid ·O 2 − generation for selective PBAT ester bond scission. Benefiting from this structural and electronic synergism, Ti-KNbO 3 achieves a 2.1-fold increase in the PTA production rate compared to pristine KNbO 3 . Furthermore, Ti-KNbO 3 demonstrates robust performance in converting post-consumer real-world PBAT products. This work provides an effective polarization and band-engineering regulation strategy for ferroelectric photocatalysts and advances the valorization of biodegradable plastic waste. Download: Download high-res image (115KB) Download: Download full-size image