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 m² 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.

Waste plastic utilization and wastewater treatment are the two most serious challenges on the path to urbanization and industrialization, due to the limited fossil fuel resources, ever-increasing energy demands, and severe environmental pollution. The conversion of waste plastics into high value-added carbon nanomaterials has become a promising way to utilize waste plastics; however, most current studies are limited to single component waste plastic; besides, little attention has been paid to porous carbon nanosheets (PCNSs). Herein, a facile approach was established to prepare PCNSs by the carbonization of real-world mixed waste plastics on organically-modified montmorillonite and subsequent KOH activation. The morphology, microstructure, textural property, phase structure, surface element composition, and thermal stability of the PCNSs were investigated. The PCNSs showed high specific surface area (2315 m² g⁻¹) and large pore volume (3.319 cm³ g⁻¹) with high purity (>99.6%). More importantly, the PCNSs exhibited fast adsorption (about 95% of methylene blue (MB) was removed during the first 10 min of adsorption), an unprecedented adsorption capacity of 769.2 mg g⁻¹ (higher than most of reported adsorbents), and excellent recyclability (after ten cycles, an adsorption capacity of 692.0 mg g⁻¹ remained and 90 wt% of the PCNS was reclaimed) for MB from wastewater. This was attributed to the high specific surface area and large pore volume of the PCNS, and due to multiple adsorption mechanisms, including pore filling, hydrogen bonding, and π–π and electrostatic interactions between MB and the PCNS. It is believed that this work not only provides a novel potential way to utilize waste plastics, but also presents a facile sustainable approach to synthesize PCNSs, which will be an ideal candidate for various applications.