Hexagonal cluster Mn-MOF nanoflowers with super-hydrophilic properties for efficient and continuous solar-driven clean water production

Abstract

Solar-driven interfacial evaporation (SDIE) is a novel, green and sustainable technology with great promise for solving the increasing freshwater scarcity crisis. However, there is still a very large gap between existing technologies and an evaporator suitable for practical applications, with high photothermal conversion ability and the required mechanical strength for continuous operation. It is imperative to develop more efficient and portable evaporators for SDIE. Due to their porous structure and hierarchical topology, metal–organic frameworks (MOFs) have attracted significant research interest in industry and in academia. Herein, a flexible Mn-MOF-based copper mesh (Mn-MCM) composite was prepared as a special evaporator for SDIE. Due to the hierarchical and porous structure of the Mn-MOF (i.e. hexagonal cluster nanoflowers), Mn-MCM possesses a high solar absorptance (86.34%) and super-hydrophilic properties (with the contact angle at 96 ms close to 0°). Under one sun irradiation, the evaporation rate of Mn-MCM can reach 1.31 kg m⁻² h⁻¹, and it can be operated continuously and stably for 8 h without any obvious decrease in efficiency. In conclusion, this work has opened up new horizons for the application of MOF-based materials in SDIE systems.