Simultaneous solar water desalination and energy generation by high efficient graphene oxide-melanin photothermal membrane

Clean water and energy remain crucial for human well-being, poverty alleviation and economic development. It has been challenging to achieve sustainable decarbonized systems, specifically for clean water and energy. Herein, we experimentally demonstrate graphene oxide–melanin (GOM) composite film with above 90 % approximate absorptivity; almost covering the entire solar spectrum. The light absorbed in presence of melanin consequently achieves 65 °C at GOM surface and yields 35.5 °C for water. GOM acts as an absolute vapor generator facilitated by vertically assembled GO channels and the solar to vapor conversion efficiency exceeds 93 % with high endurance up to 1.6 kg m−2 h−1 for water. The water evaporation rate in presence of mixed salts ranges in between 1.05 and 1.35 kg m-2 h-1 with 66–86 % efficiency depending on solution chemistry. Furthermore, we exploit simultaneous clean water and energy system by combining thermoelectric technology. The TEG device can produce a maximum power density of 0.9 W m−2 at relative humidity of 60 %. All of these results demonstrate synergistic effects of GOM, effective heat dissipation and utilization with continuous water transport. This work provides new understandings on the interplay between water and energy context. [Display omitted] •A simple strategy is proposed to fabricate melanin on graphene oxide (GOM).•GOM composite has excellent light absorption and covers the entire solar spectrum.•GOM photothermal membrane has higher solar-thermal efficiency and heat dissipation.•GO water channels enhance the water evaporation efficiency and energy generation.•GOM has great potential for sustainable desalination and energy generation.