Nanocellulose-Based Interfacial Solar Evaporator: Integrating Sustainable Materials and Micro-/Nano-Architectures for Solar Desalination

Clean-water harvesting through solar interfacial evaporation technology has recently emerged as a strategy for resolving global water scarcity. In this study, rapid carbon-dioxide-laser-induced carbonization and facile ice-templating is employed to construct a cellulose-based solar evaporator bearing a hybrid multi-layer micro-/nano-architecture (i.e., a laser-induced carbon (LC) nanostructure and a cellulose aerogel (CA) nano/microstructure). The LC exhibits a light-absorbing/photothermal nanoporous carbon structure that offers high light absorption and multiple light scattering. Additionally, the CA exhibits numerous nanopores and unidirectional microchannels that facilitate rapid water transport via capillary action. This hybrid LC/CA micro-/nano-architecture enabled rapid vapor generation with an average water evaporation rate (ν) of 1.62 kg m⁻² h⁻¹ and an evaporation efficiency (η) of 66.6%. To further enhance the evaporation performance, a polydimethylsiloxane (PDMS) layer is coated onto the side of the LC/CA evaporator to increase its floatability in the simulated water; ν and η of the PDMS-coated LC/CA evaporator (LC/CA/PDMS) increased to 1.9 kg m⁻² h⁻¹ and 83.8%, respectively. Additionally, the LC/CA/PDMS evaporator exhibited a high ν value of 1.68 kg m⁻² h⁻¹ in simulated seawater, originating from excellent resistance to salt accumulation via its self-cleaning ability. Furthermore, the solar evaporator exhibited scalability for fabrication as well as biodegradable properties.