Controllable synthesis of sea urchin-like carbon from metal-organic frameworks for advanced solar vapor generators

Solar evaporation is considered as a hopeful technology for producing freshwater from non-potable water using inexhaustible solar energy. However, solar evaporators with high performance and good scalability are still urgently needed. Herein, a bilayer solar evaporator is prepared by facilely coating natural wood with carbon materials pyrolyzed from sea urchin-like metal–organic frameworks (MOFs). The carbon materials inherit the sea urchin-like morphology and grow bamboo-like carbon nanotubes wrapping Ni nanoparticles, which synergistically contribute to the efficient light trapping and thermal harvesting. Meanwhile, the doped nitrogen and oxygen enhance the hydrophilicity of carbon materials. In another aspect, wood not only provides abundant hydrophilic channels for sufficient water supply, but also reduces the water evaporation enthalpy by 26% through the hydrogen bonds between water and hydrophilic groups of wood. With the combined merits above, the bilayer solar evaporator achieves high sunlight absorption (98%), low thermal conductivity (0.17 W m−1 K−1), rapid water transport, and low vaporization enthalpy. Consequently, the solar evaporator exhibits a notable water evaporation rate of 2.07 kg m-2 h−1 under 1 Sun irradiation, surpassing that of reported MOFs or wood-based evaporators. Importantly, a large-scale solar desalination device is developed for outdoor experiments to obtain freshwater from seawater. The daily freshwater production amount per unit area (2.74 kg) meets the daily water consumption requirement of one adult. This work states the great potential of MOFs-derived carbons for efficient solar vapor generation and opens an avenue for application in energy storage and conversion.