Ultra‐Black Pinecone for Efficient Solar Steam Generation under Omnidirectional Illumination

Abstract

Abstract It has been a goal to create artificial evaporators that have highly efficient solar steam generation (SSG) performance under omnidirectional illumination to solve the global drinking water crisis. Although some evaporators with high evaporation rates and efficiencies have been reported, their inefficient performance under oblique illumination conditions remain to be overcome. Pinecones, with their delicate transpiration channels, photo‐thermal moisture‐sensitive deployable structure, and 3D Fibonacci helically‐arranged scales, inspire the design of this efficient evaporator under omnidirectional illumination. Herein, ultra‐black pinecone (UBP) with multi‐branched, arterially porous, and hierarchical structures shows excellent SSG performance under omnidirectional illumination. UBP achieves a high evaporation rate and efficiency of 1.86 kg m −2 h −1 and 97.85% respectively, under one sun illumination. The SSG performance under oblique incidence conditions of UBP are not degraded but improved (2.194 g h −1 under incident angle of 90°) because the UBP can recover reflection and radiation energy losses, avoid cosine energy losses, and absorb heat from the warm environment. The UBP also exhibits high evaporation rate in real weather and good durability and salt resistance in concentrated brine, which ensures its great potential applications in wastewater treatment and solar desalination.