Repurposing spent battery waste into plasmonic photothermal membrane for efficient solar-driven evaporation and...

Freshwater scarcity is an escalating global challenge that affects billions of people. Conventional desalination methods remain constrained by significant energy consumption, high operational costs, and the generation of secondary pollutants. Solar-driven water evaporation has recently emerged as an eco-friendly alternative, where the design of photothermal materials plays a critical role in overall performance. Many existing materials are costly and environmentally concerning, underscoring the need for sustainable, low-cost solutions. In this study, we present a novel photothermal material synthesized from spent battery powder (SBP), an electronic waste with poor recycling rates, functionalized with plasmonic silver nanoparticles (AgNPs). AgNPs were deposited on SBP through a tannic acid-assisted in situ reduction process, yielding SBP-Ag particles, which were subsequently coated onto a cellulose membrane via vacuum filtration. The resulting SBP-Ag membrane exhibited strong solar absorption, rapid photothermal conversion, and robust stability. Under 1 sun illumination, it achieved a high evaporation rate of 2.44 kg m^-2h^-1 with a solar vapor generation efficiency of 88.93%. Furthermore, the membrane demonstrated excellent multi-cycle stability, chemical resistance across a wide pH range, and effective desalination and water purification performance. This work highlights a sustainable and scalable strategy to repurpose battery waste into a high-performance photothermal material, advancing eco-friendly solar-driven water evaporation for freshwater production.