Rational Design of High‐Performance Bilayer Solar Evaporator by Using Waste Polyester‐Derived Porous Carbon‐Coated Wood

Abstract

Wood‐based bilayer solar evaporators, which possess cooperative advantages of natural wood and photothermal conversion coating including fast water transportation, low heat conduction, renewability, and high light absorbability, hold great promise for water purification. However, previous studies suffer from low evaporation rates and high cost of coatings, and lack a deep understanding how the porous structures of coating layer function. Herein, a novel bilayer solar evaporator is designed through facile surface coating of wood by low‐cost porous carbon from controlled carbonization of polyester waste. The porous carbon bears rich oxygen‐containing groups, well‐controlled micro‐/meso‐/macropores, and high surface areas (1164 m 2 g −1 ). It is proved that porous carbon improves sunlight absorption and promotes the formation of numerous water clusters to reduce water evaporation enthalpy. Owing to these combined features, the bilayer solar evaporator exhibits high evaporation rate (2.38 kg m −2 h −1 ), excellent long‐term stability, and good salt resistance. More importantly, a large‐scale solar desalination device for outdoor experiments is developed to produce freshwater from seawater. The daily freshwater production amount (3.65 kg m −2 ) per unit area meets the daily water consumption requirement of one adult. These findings will inspire new paradigms toward developing efficient solar steaming technologies for desalination to address global freshwater shortage.