Photothermal Mineralization of Polyolefin Microplastics via TiO<sub>2</sub> Hierarchical Porous Layer-Based Semiwetting Air-Plastic-Solid Interfaces.

Zhao, Jiaqi; Miao, Peng; Zhang, Xuerui; Wang, Pu; Li, Zhenhua; Wu, Li-Zhu; Shi, Run; Zhang, Tierui · Adv Mater · 2024

basic_science · Level V

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Abstract

Photo-mineralization of microplastics under mild conditions has emerged as a promising solution to plastic waste disposal. However, the inadequate contact between oxygen, water-insoluble polyolefin microplastics, and photocatalysts remains a critical issue. In this study, a TiO<sub>2</sub> hierarchical porous layer (TiO<sub>2</sub>-HPL) photocatalyst is presented to establish air-plastic-solid triphase interfaces for the photothermal mineralization of polyolefins. The wettability of the TiO<sub>2</sub>-HPL-based triphase interface is finely controlled from plastophobic to plastophilic. High-resolution imaging and finite element simulation demonstrate the significance of a semiwetting state in achieving multidirectional oxygen diffusion through the hierarchical pore structure while maintaining sufficient contact between the plastic phase and photocatalysts. For low-density polyethylene, the TiO<sub>2</sub>-HPL achieves a photothermal mineralization rate of 5.63 mmol g<sup>-1</sup> h<sup>-1</sup> and a conversion of 26.3% after 20 h of continuous irradiation. Additionally, the triphase photocatalytic system with semiwetting gas-plastic-solid interfaces shows good universality for various polyolefin reagents and products, illustrating its potential in achieving efficient photothermal mineralization of non-degradable microplastics.