Porous rGO-MBene monolith: A highly efficient solar evaporator for salt-resistant desalination and multitasking water purification

Abstract

Solar-driven water evaporation for sustainable freshwater production is an efficient and economical solution to alleviate global water shortages. However, available solar evaporators still face efficiency and durability limitations. Herein, this challenge is overcome via the ingenious design of a three-dimensional (3D) monolithic porous architecture based on the reduced graphene oxide (rGO) and layered molybdenum boride (MBene). Benefiting from broad light absorption, efficient water activation and porous architecture feature, the rGO-MBene acquires an impressive rate of ~2.79 kg·m−2·h−1 to steam pure water under one-sun (1 kW/m2), which is superior to most of state-of-the-art graphene-based evaporators reported so far. When applied to solar desalination, the rGO-MBene exhibits highly durable desalination capability with a salt-free evaporation surface. After continuous irradiation in a 3.5 % NaCl solution for 100 h, an almost constant evaporation rate of approximately 2.34 kg·m−2·h−1 can be maintained. Meanwhile, the rGO-MBene evaporator also demonstrates its robustness for effective production of freshwater from various wastewater sources. This work not only establishes an attractive example of rGO-hybridized architecture to achieve highly efficient solar evaporation for long-lasting salt-resistant desalination and multitasking water purification, but also provides exciting opportunities to design new MBene-based materials with the improved photothermal performance for sustainable solar conversion.