Polypyrrole/Silver-Coated Hierarchical Durian Shells: Synergistic Photothermal Conversion and Antibacterial Activity for Sustainable Solar Desalination

Abstract Interface solar evaporation, as a green and efficient water treatment technology, offers a sustainable approach to addressing global freshwater scarcity. However, the design of interfacial solar evaporators with high evaporation rate, salt resistance, and durability in complex water environments remains a significant challenge. Herein, we present a biomass-derived 3D evaporator (DS@PPy@Ag) fabricated by in-situ polymerization of polypyrrole (PPy) and deposition of silver (Ag) nanoparticles on durian shells (DS). Benefiting from the inherent “cone-pore” structure of DS and the photothermal effect of PPy and Ag nanoparticles (Ag NPs), DS@PPy@Ag achieves enhanced broadband optical absorption and exhibits a projected-area-normalized evaporation rate of 2.80 kg·m−2·h−1 under 1 sun, outperforming most reported biomass-based evaporators. The synergistic effect of structural induction and interfacial transport mechanisms enables DS@PPy@Ag to demonstrate effective salt self-desalting and resistance under high-salinity conditions. Outdoor tests demonstrate a peak freshwater yield of 1.67 kg·m−2·h−1 with >99% ion removal, efficient organic pollutant removal, and broad-spectrum antibacterial activity. This work highlights a structure−function integrated strategy using biomass waste and photothermal components, providing a scalable and low-cost platform for efficient solar-driven freshwater production and wastewater purification.