A self-floating Janus PPy@Ni sponge salt-resisting solar evaporator for efficient interfacial evaporation

Abstract

Interfacial water evaporation has emerged as one of the environmentally friendly technologies for seawater desalination and wastewater treatment. However, salt deposition issuesignificantly threaten the long-term stability of the evaporation system. Herein, we prepared a low-density nickel sponge (NSP) with porous network structure via a hydrothermal route. After polypyrrole (PPy) coating and hydrophilic modification, the NSP can be fabricated into a Janus evaporator (PPy-NSP). Benefiting from the PPy coating and rough skeleton, the light absorption of PPy-NSP evaporator is enhanced by up to 97.5%. Combined with the wide-spectrum solar absorption of PPy and porous network architectures, the Janus evaporators feature an outstanding evaporation rate of 1.71 kg m−2h−1 under one sun irradiation. Moreover, the asymmetric wettability of the PPy-NSP evaporator effectively prevents salt deposition, which shows excellent salt resistance performance even in 15% wt% NaCl brine. Further testing reveals that the evaporator also exhibits excellent purification effects on dye solutions and heavy metal ions wastewater. The PPy-NSP evaporator also possesses magnetic properties, self-floating, and environmental friendliness, which may hold great potential applications in desalination, sewage treatment, and electromagnetic shielding.