Simultaneous Solar-Driven Interfacial Evaporation and Photo-Fenton Oxidation by Semiconducting Metal–Organic Framework From Waste Polyimide

The integrated technology of interfacial solar steam generation and photo-Fenton oxidation has emerged as a promising way to simultaneously mitigate freshwater scarcity and degrade organic pollutants. However, fabricating low-cost, multi-functional evaporators with high water evaporation and catalytic ability still presents a significant challenge. Herein, we report the functional upcycling of waste polyimide into semiconducting Fe-BTEC and subsequently construct Fe-BTEC-based composite evaporators for simultaneous freshwater production and photo-Fenton degradation of pollutants. Firstly, through a two-step solvothermal-solution stirring method, Fe-BTEC nanoparticles with the size of 20–100 nm are massively produced from waste polyimide, with a band gap energy of 2.2 eV. The composite evaporator based on Fe-BTEC and graphene possesses wide solar-spectrum absorption capacity, high photothermal conversion capacity, rapid delivery of water, and low enthalpy of evaporation. Benefiting from the merits above, the composite evaporator achieves a high evaporation rate of 2.72 kg m⁻² h⁻¹ from tetracycline solution, as well as the photothermal conversion efficiency of 97% when exposed to irradiation of 1 Sun, superior to many evaporators. What is more, the evaporator exhibits the tetracycline degradation rate of 99.6% with good recycling stability, ranking as one of the most powerful heterogeneous Fenton catalysts. COMSOL Multiphysics and density functional theory calculation results prove the synergistic effect of the concentrated heat produced by interfacial solar steam generation and catalytic active sites of Fe-BTEC on promoting H₂O₂ activation to form reactive oxidation radicals. This work not only provides a green strategy for upcycling waste polyimide, but also proposes a new approach to fabricate multi-functional evaporators.