Carbonized sorghum straw derived 3D cup-shaped evaporator with enhanced evaporation rate and energy efficiency

Solar-driven evaporation is considered as one of potential approaches to circumvent the global crisis of fresh water shortage. Various two-dimensionally (2D) devices have been reported, but the evaporation rate and energy efficiency have approached their limit. In this study, we proposed a three-dimensional (3D) cup-shaped evaporator based on carbonized sorghum straw (CSS), and the wall of the 3D evaporator can efficiently absorb the reflected light and thermal radiation heat loss. The good optical absorption property, super-hydrophilic characteristic and well heat-shielding performance of CSS endow the 3D cup-shaped evaporator with excellent evaporation rate (3.27 kg m −2 h −1 ) and energy efficiency (131.2%) under 1 Sun illumination. The 3D cup-shaped evaporator also demonstrates excellent resistance salt ability and good resistance to acid and alkali during producing clean water from seawater and wastewater. The prepared 3D cup-shaped evaporator not only provides a novel solution to combating the scarcity of fresh water but also inspires new paradigm toward breaking through the energy efficiency limit of 2D devices. • A 3D cup-shaped evaporator based on carbonized sorghum stalk was constructed. • The evaporator can recover the reflected light and reduce thermal radiation heat loss. • High evaporation rate (3.27 kg m −2 h −1 ) and energy efficiency (131.2%) were obtained. • The evaporator was successfully applied to desalination and wastewater treatment.