All-weather photothermal-electrothermal integrated system for efficient solar steam generation

Abstract

Interfacial solar-driven water evaporation is considered as an economic and efficient strategy to address the shortage of freshwater resources, which however suffers from severe salt pollution and poor long-term stable performance of seawater evaporation. Here, we design and construct a three-dimensional all-weather solar evaporator by zeolite-chitosan-TiO2@PPy aerogel (ZCTP), with an internally oriented pore arrangement structure by zeolite and chitosan assistance, which can efficiently enhance solar-driven water purification. Most importantly, long-term operation of the ZCTP aerogels using carbon fiber heating wires to fully utilize the solar energy that collected during the daytime to improve the efficiency of solar utilization and water purification. Benefiting from novel structural and functional design, the ZCTP aerogels exhibit high broadband light absorption (96 %), fast water transport (13 ms), and good thermal management properties (thermal conductivity of 0.1969 W m−1 K−1 in wet state). The obtained results show that the water evaporation rate of the ZCTP aerogel is 1.66 kg m-2h−1 under 1 sun illumination. The integrated system of photothermal and electrothermal energy conversion mechanisms obtains an ultra-high water evaporation rate of 11.70 kg m-2h−1 of 5 V voltage under 1 sun irradiation, achieving the purpose of continuous purification water around the clock. In addition, excellent salt resistance also enables perfect stability and reusability of ZCTP aerogel, even in the water with 20 % salt having minimal impact on the evaporation process and energy efficiency. Based on its excellent mechanical stability and highly ductility, simple and scalable manufacturing process, ZCTP aerogel may have great potential for all-weather efficient photothermal material for large-scale applications such as wastewater treatment, seawater desalination, and solar steam generation.