Copper nanodot-embedded graphene urchins of nearly full-spectrum solar absorption and extraordinary solar desalination

Abstract

Black materials are the key to convert solar light to thermal energy, but it is not easy to economically achieve full solar-spectrum light absorption and maximally harvest solar energy. Herein, we develop a “popcorn” approach based on a space-confined pyrolysis of copper carbodiimide to synthesis Cu nanodot-embedded N-doped graphene urchins. In situ formed Cu nanodots are rigidly fixed and spatially scaffolded in the graphene matrix, achieving nearly full-spectrum solar light absorption (99%) over a wide spectral range (300–1800 nm). Such a highly efficient solar harvest is endowed by an intensively hybridized localized surface plasmon resonance and stabilized by graphene matrix. When applied in solar desalination, the N-doped graphene urchins provide structural interconnectivity and freeway for water transports and enable the as-formed plasmonic absorber to naturally self-float on water. By localizing the absorbed energy at the interfaces, efficient (~ 82%) and stable desalination is ultimately achieved under a simulated solar light. Practically, a solar desalination system of the plasmonic absorber can produce fresh water with a rate of ~ 5 L m−2 day−1 under solar irradiation.