Scalable and Highly Efficient Mesoporous Wood‐Based Solar Steam Generation Device: Localized Heat, Rapid Water Transport

TLDR

Solar steam generation is a sustainable method for desalination and wastewater treatment, yet scalable, high‑efficiency materials under 1 Sun are lacking. The authors design a solar steam generation device that exploits cross‑plane water transport in mesoporous wood through nanoscale channels to minimize conductive heat loss. The device uses cellulose nanofibers circularly oriented around pits and aligned along spirals to draw water across lumens, while the anisotropic thermal conduction of the wood redirects absorbed heat in‑plane and reduces its conductivity to 0.11 W m⁻¹ K⁻¹, outperforming Styrofoam insulation. The device achieves 80 % steam‑generation efficiency at 1 Sun and 89 % at 10 Sun, demonstrates rapid water transport via pits and spirals, and shows promise for cost‑effective, large‑scale application under ambient solar irradiance.

Abstract

Abstract Solar steam generation is regarded as one of the most sustainable techniques for desalination and wastewater treatment. However, there has been a lack of scalable material systems with high efficiency under 1 Sun. A solar steam generation device is designed utilizing crossplane water transport in wood via nanoscale channels and the preferred thermal transport direction is decoupled to reduce the conductive heat loss. A high steam generation efficiency of 80% under 1 Sun and 89% under 10 Suns is achieved. Surprisingly, the crossplanes perpendicular to the mesoporous wood can provide rapid water transport via the pits and spirals. The cellulose nanofibers are circularly oriented around the pits and highly aligned along spirals to draw water across lumens. Meanwhile, the anisotropic thermal conduction of mesoporous wood is utilized, which can provide better insulation than widely used super‐thermal insulator Styrofoam (≈0.03 W m −1 K −1 ). The crossplane direction of wood exhibits a thermal conductivity of 0.11 W m −1 K −1 . The anisotropic thermal conduction redirects the absorbed heat along the in‐plane direction while impeding the conductive heat loss to the water. The solar steam generation device is promising for cost‐effective and large‐scale application under ambient solar irradiance.