Reduced graphene oxide/FeOOH-based asymmetric evaporator for the simultaneous generation of clean water and electrical power

As one of the ways to comprehensively utilize solar energy, solar-driven interfacial evaporation displays promising opportunities to alleviate both freshwater and energy shortages. However, there is always a partial impairment of solar energy utilization during evaporation, and its operation is stagnant without sunlight. In this study, a novel asymmetric evaporator is designed that achieves the maximum utilization of solar energy for clean water and power output by two-step asymmetric filtration of reduced graphene oxide/FeOOH (RGO/FeOOH)-based composites and graphene oxide (GO) on a mixed cellulose ester membrane (MCE). Under one solar irradiation, the RGO/FeOOH-based asymmetric evaporator can achieve an average output power of 51.33 mW m−2 synchronously with efficient solar evaporation. The output voltage can reach up to 640 mV with a current of approximately 84.8 μA. Furthermore, the average output power of this evaporator is 26.96 mW m−2 under ambient conditions. A light-emitting diode (LED) can be successfully lit via a series connection of electricity generators. The RGO/FeOOH-based asymmetric evaporator can function full-time with only solar energy and water, demonstrating the potential to generate steam and electricity simultaneously in sunlight; the findings also show its value as a generator on cloudy days or at night. Moreover, the RGO/FeOOH-based composites also show the photocatalytic degradation capabilities of organic pollutants in water. The simple fabrication strategy and superior thermal and electrical performance of the solution indicate that these novel RGO/FeOOH-based composites can be used for power generation, energy storage and brine and wastewater purification to achieve the maximum utilization of resources.