High efficiency solar interfacial evaporator for seawater desalination based on high porosity loofah sponge biochar

•A novel biochar solar interfacial evaporator was developed.•The solar absorption layer and substrate were optimized.•The evaporation rate of loofah-based evaporator reached 1.565 kg m−2 h−1.•The evaporation efficiency of loofah-based evaporator reached 80.66%.•The quality of produced freshwater meets the standard of domestic water.