Achieving solar-thermal driven dual functional device utilizing flexible PDA coated sponge integrated thermoelectric module design for water purification and power generation

The design of an efficient solar energy collector for solar-thermal-driven water purification and power generation is a promising strategy to concurrently mitigate the shortage of fresh water and energy crises. However, harvesting low-grade thermal energy in an eco-friendly and cost-effective manner through solar-thermal materials for water evaporation and electric cogeneration remains challenging. Herein, we demonstrate a dual-functional device integrating solar-thermally driven water purification and thermo-induced power generation. This typical design, fabricated via polydopamine (PDA) tightly deposited onto melamine sponges (PDA@Sponge) via H-bonds, along with a thermoelectric generator (PDA@Sponge/TEG), showcases superior solar-thermal-driven dual-functional application. The critically structurally adjustable PDA@Sponge possesses excellent homogeneity and stability, weakening interfacial hydrogen bonding between water molecules, favoring the evaporation and overflow of water molecules. The optimal serrated design achieves a water evaporation rate of up to ∼1.50 kg  −2 h −1 , with an efficiency of ∼ 94.04 % under one sun, surpassing the most of previous reports, owing to its special tip thermal localization effect and rational water transportation management. Simultaneously, the designed PDA@Sponge/TEG yields an open-circuit voltage and short circuit current of 55 mV and 22 mA, respectively, along with a maximal output power of 162 μW (40.5 μW/cm 2 ) at a load resistance of 7.5 Ω, under one sun and room temperature. Notably, such a device, after multiple series connections, can charge a capacitor to 1.5 V within 1 min, capable of powering low-energy electronic devices such as smartwatches and LED lights. By efficiently integrating of multiple solar-thermal-driven processes, our research promotes the design of multifunctional devices to promise an approach for desalinating seawater, purifying wastewater, and powering low-energy electronics, especially in remote areas lacking power stations and/or water treatment facilities.