Transforming waste polyester into porous carbon polyhedron for interfacial solar steam and hydrovoltaic electricity co-generation

The integration of interfacial solar steam generation with water evaporation-driven electricity generation is regarded as one of the most hopeful strategies for addressing global energy and freshwater crises. However, constructing low-cost, multi-functional porous carbon materials-based devices for freshwater-electricity co-generation remains challenging. Herein, we report the preparation of porous carbon polyhedron (PCP) by the controllable carbonization of barium-based metal–organic frameworks produced by the two-step ball milling of waste polyester bottles, and subsequently fabricate PCP-based solar evaporators and energy harvesting devices, capable of freshwater production and electrical energy generation all day. The as-prepared PCP evaporator owns good hydrophilicity, sunlight absorption, excellent photothermal conversion capability as well as low evaporation enthalpy. Under 1 Sun irradiation, it exhibits the evaporation flux of 2.74 kg m-2h−1 as well as the conversion efficiency of 98.2 %. Importantly, the PCP evaporator-based energy generation device realizes the open-circuit voltage of 212 mV, along with the good cycling stability. The well-developed pore channels, large specific surface area, and abundant functional groups are proved to be key parameters for electricity generation. Furthermore, the density functional theory model result unravels that the as-formed potential field inhibits OH–, thus creating a potential difference between upper and lower terminals. This research outlines a "Win-Win" strategy aimed at achieving environmentally friendly, high-value repurposing of waste polyester. Additionally, it aims to develop sophisticated co-generation devices for producing both freshwater and electricity.