Turning trash into treasure: Integrating waste MXene sediment with bagasse into photothermal composite aerogel for efficient solar-driven interfacial evaporation

Abstract

Solar-driven interfacial evaporation (SDIE) technique holds significant potential in addressing the global freshwater scarcity issue. Using waste resources to construct an evaporator is the promising choice for SDIE with low energy consumption, low cost, and sustainability. Herein, an aerogel photothermal evaporator composed of waste MXene sediment (WM) and bagasse-derived cellulose was demonstrated. WM was a mixture of outstanding light absorption and photothermal conversion. Cellulose served as the skeleton. Besides, the ordered vertical microchannel array within the aerogel evaporator (WM/BCA) was successfully fabricated using a super-frozen ice crystal as a template during the directional freeze process. The excellent photothermal characteristic of WM and the unique microstructure of aerogel endowed the high light absorption, superior hydrophilicity, rapid water transport, and salt reflux of composite evaporator. Benefiting from the above advantages, the optimal sample (WM/BCA-3) demonstrated excellent water evaporation, desalination ability, and long-term stability. Furthermore, the effect of aerogel evaporator size on evaporation was investigated. The evaporation rate was enhanced to 2.03 kg·m−2·h−1 (deionized water as source) with 94.5 % solar efficiency through the reduction in diameter of the aerogel evaporator, while an increase in the number of aerogels facilitated an improvement in vapor yield. Finally, an outdoor test exhibited the practical application potential of composite aerogel in freshwater production. This work presents a promising approach to constructing and optimizing an efficient solar-driven interfacial evaporator using waste materials.