Efficient interfacial solar-driven evaporation and hydroelectric co-generation by Al-Fum metal-organic framework-derived porous carbon

The combination of solar-driven water evaporation and power generation provides a promising approach to alleviate energy problem and freshwater shortage. However, developing multi-functional materials for water evaporation and power co-generation remains challenging. Herein, porous carbon polyhedra (PCP) is synthesized by the controlled carbonization of aluminum fumarate metal-organic framework (Al-Fum MOF) for fabricating water evaporation and energy harvesting devices. Under 1 Sun irradiation, the evaporation rate is up to 2.84 kg m⁻² h⁻¹, accompanied by the photothermal conversion efficiency of 98.8 %. Additionally, the power generation unit based on the PCP evaporator achieves the open-circuit voltage of 197 mV, exhibiting commendable cycle stability. The rich pore structure and abundant oxygen-containing functional groups are pivotal parameters for power generation. The result of molecular dynamics simulation indicates that the negatively charged ions are inhibited in the nanochannels of the negatively charged PCP surface, resulting in the Na⁺ concentration difference, triggering the potential difference. This study reveals the mechanism on water evaporation and power co-generation in porous carbon materials, and offers a pathway for the development of advanced devices for water production and hydropower co-generation.