Bimetallic Co/Fe-MOF derived from poly(butylene adipate-co-terephthalate) (PBAT) plastic wastes for efficient interfacial solar steam generation

The conversion of waste plastics into metal-organic framework (MOF) photothermal materials presents promising opportunities for solar energy conversion, facilitating freshwater production and water purification through interfacial solar evaporation, and simultaneously heralding advancements in plastic waste recycling. Herein, we present a bimetallic Co/Fe-MOF photothermal converting material derived from PBAT-based plastic wastes, tailored for efficient solar water evaporation. The nanosheet-structured bimetallic Co/Fe-MOF featuring high light absorption, water wettability and photothermal conversion efficiency delivers an optimal evaporation rate of 1.81 kg m⁻² h⁻¹ under one sun irradiation, surpassing that of monometallic MOFs. Moreover, we employed three substrates—nanofiber film, aerogel, and hydrogel—to immobilize the Co/Fe-MOF solar absorbers, thereby constructing monolithic hybrid solar evaporators. These substrates not only confer the flexibility to Co/Fe-MOF solar absorbers for practicability but also serve as mediates to regulate thermal management and water states. Consequently, the hybrid evaporators exhibited significantly enhanced evaporation rates, with the hydrogel evaporator achieving to ~3.53 kg m⁻² h⁻¹, coupled with remarkable salt resistance and durability. This bimetallic Co/Fe-MOF-based solar evaporator efficiently serves a dual purpose, enhancing clean water production through solar desalination and purification while also presenting a viable alternative to the issue of plastic waste, potentially harmonizing energy, environment and clean water nexus.