Biogenic Cu_2-xSe nanoparticles with vacancy engineering quickly upcycle cobalt from wastewater for photothermal...

Sustainable upcycling of cobalt (Co) from wastewater into functional nanomaterials offers an eco-friendly solution for resource recovery. However, conventional approaches are limited by energy-intensive processes and reliance on microbial detoxification processes such as extracellular electron transfer (EET). Here, we propose a vacancy-driven biosynthesis strategy that circumvents conventional EET pathways, achieving ultrafast (<10 s) Co²⁺ doping into biogenic Cu_2-xSe nanoparticles (bio-Cu_2-xSe) through vacancy-mediated lattice substitution. Shewanella oneidensis MR-1 synthesizes vacancy-rich bio-Cu_2-xSe as a scaffold for spontaneous Co²⁺ immobilization, eliminating the need for chemical additives or energy-intensive processing. The resulting bio-(Co,Cu)Se₂ derived from real electroplating wastewater treatment exhibits intrinsic photothermal activity, achieving a rapid temperature elevation (ΔT = 36.5 °C under 1 sun illumination) and enabling complete bacterial inactivation through photothermal-mechanical synergy under visible light irradiation. The photothermal membrane fabricated using bio-(Co,Cu)Se₂ achieves an outstanding solar evaporation efficiency of 93.40 %, ranking among the highest-performing plasmon-enhanced systems reported in this field. Compared to conventional synthesis, our biohybrid nanomaterial matches the performance of chemically synthesized counterparts while reducing costs by 44-61 %. This vacancy engineering strategy establishes a rapid, low-carbon metal upcycling platform applicable to diverse metal pollutants, advancing scalable sustainable nanotechnology.