Multifunctional graphene/Ag hydrogel with antimicrobial and catalytic properties for efficient solar-driven desalination and wastewater purification

The increasing shortage of freshwater resources needs to be addressed urgently. Solar-driven desalination and wastewater purification are efficient and green methods to obtain freshwater resources. However, it is still a challenge to obtain efficient, stable, salt-resistant, antimicrobial, and antifouling evaporators. To address this challenge, in this study, polyacrylamide-based reduced graphene oxide hydrogels with a porous structure were synthesized in situ by a one-step radiative reduction method, and silver nanoparticles were introduced on this basis. Graphene/silver composite hydrogel (ArG-Ag) exhibits fast water transport, thermal localization, and low enthalpy of water evaporation, achieving an excellent evaporation rate of 3.089 kg m-2h−1 (one sun) and an evaporation efficiency of 122.7 %, as well as good mechanical stability, salt resistance, and salt ion purification after 8 cycles of evaporation. The ArG-Ag evaporator exhibits 99 % 24 h bacterial inhibition against E. coli and 210-day long-term mold resistance, effectively resisting biological contamination of seawater. In this study, multifunctional evaporators with integrated high efficiency evaporation performance, salt resistance, antimicrobial, antifungal, antifouling, and catalytic properties are proposed, which are expected to be used for seawater desalination and wastewater purification.