A decoupled and scalable solar evaporator integrating boron-enhanced polypyrrole photothermal fabric for efficient water purification

Abstract

Interfacial solar evaporation suffers a significant barrier in achieving a balance between significant photothermal efficiency, facile synthesis and long-term stability. Herein, this paper introduces a facile fabrication of functionally decoupled solar evaporation design that addresses this problem by strategic layer separation. For this, polypyrrole coatings of boron nanoparticle (B@PPy) is successfully carried out by scalable in situ polymerization for the construction of efficient photothermal materials. This scalable process was employed to cotton fabric (B@PPy) to construct a decoupled solar evaporator, thermally isolated by a polyethylene terephthalate (PET) foam, effectively minimizing parasitic heat loss. Importantly, a separate, unmodified white cotton cloth acts as a specific water transport pathway, wicking water directly from a reservoir to the evaporation interface without affecting the photothermal surface. This decoupled design, which physically separates light absorption, thermal insulation, and water supply, allows for excellent thermal localization. Under 1 sun irradiation, the evaporator achieves a high evaporation rate of 1.90 kg m⁻² h⁻¹ with a solar-thermal conversion efficiency of 92.5%. This study presents a scalable, material-efficient, and architecturally sophisticated approach for high-performance, maintenance-free solar desalination, paving the way for viable off-grid water purification solutions.