Oxygen-enriched tubular carbon for efficient solar steam generation

Carbon materials with excellent light-harvesting capacity are promising light absorbers for solar-thermal conversion. However, developing advanced carbon materials with tailored morphology and properties that are suitable for solar steam generation remains challenging. Herein, we have successfully synthesized oxygen-enriched tubular carbon with uniform hollow architecture and some defective structure by pyrolysis of a coordination complex (PEG-CaCl₂ precursor). Briefly, PEG molecules can promote the anisotropic growth of CaCl₂ nanorods during pyrolysis through coordination interaction (Ca–O), and simultaneously serve as the carbon and oxygen sources for in-situ growth of self-doped tubular carbon using the as-formed nanorods as ideal templates. The resulting tubular carbon with one-dimensional hollow structure, possesses a large specific surface area (613 m² g⁻¹) for light absorption, low thermal conductivity (0.0474 W m⁻¹ K⁻¹) for heat localization, and abundant hydrophilic oxygen-containing groups (8.62 at.% oxygen) for efficient water delivery. Thus, the self-floating photothermal membrane based on the tubular carbon, fabricated by the addition of agar binder, exhibits broadband light absorption (96%) and achieves a high evaporation efficiency of 91.3% under one sun illumination. This work provides a new insight to design and synthesize functionalized carbon with controlled morphology and the desired structure for potential application in solar steam generation. © 2020 Published by Elsevier Ltd.