Synergy of Light Trapping and Water Management in Interconnected Porous PEDOT:PSS Hydrogels for Efficient Solar-Driven Water Purification

Interfacialsolar water purification is emerging as a sustainableand environmental-friendly approach for solar energy harvesting andclean water production. Currently, the limited photothermal conversionefficiency restricts its practical applications. Developing evaporatorswith porous structures has been proposed as a promising way towardboosting solar-thermal-vapor conversion by enhancing energy utilizationand evaporation area. However, effective collaboration between lightcapture and water management of porous evaporators is the main challengefor efficient freshwater production. Here, we reported a pure poly-(3,4-ethylenedioxythiophene)(PEDOT):polystyrene sulfonate (PSS) hydrogel by in situ polymerization as a solar evaporator for water purification fromsaline water or wastewater. The interconnected and microporous structureof the PEDOT:PSS hydrogel (PPH) can dramatically trap light throughoutbroad incident angles as well as increase the active water contentsimultaneously, which is highly controlled by the PSS content. ThePPH could efficiently convert the absorbed solar energy and wastewaterinto fresh water, thus leading to an excellent photothermal conversionefficiency of 96.4% and an evaporation rate of 2.43 kg & BULL;m(-2)& BULL;h(-1) during purification of3.5 wt % NaCl brine under one sun irradiation. This PPH exhibits sustainableand stable performance in 88 h when purified with 3.5 wt % simulatedsaline water, with an evaporation rate of & SIM;2.32 kg & BULL;m(-2)& BULL;h(-1). What is more, this PPHperforms satisfied performance in water purification (with the concentrationof all ions dropping below 1 mg & BULL;L-1) from salinewater, dye, and heavy metal wastewater. These results demonstratethat high evaporation performance could be achieved if effective lighttrapping and water management are ensured simultaneously. Thus, thisstudy provides a new possibility for long-term, stable, and efficientwater purification from wastewater.