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Title: Size tunable elemental copper nanoparticles: extracellular synthesis by thermoanaerobic bacteria and capping molecules

Bimodal sized elemental copper (Cu) nanoparticles (NPs) were synthesized from inexpensive oxidized copper salts by an extracellular metal-reduction process using anaerobic Thermoanaerobacter sp. X513 bacteria in aqueous solution. The bacteria nucleate NPs outside of the cell, and they control the Cu2+ reduction rate to form uniform crystallites with an average diameter of 1.75 0.46 m after 3-day incubation. To control the size and enhance air stability of Cu NPs, the reaction mixtures were supplemented with nitrilotriacetic acid as a chelator, and the surfactant capping agents oleic acid, oleylamine, ascorbic acid, or L-cysteine. Time-dependent UV-visible absorption measurements and XPS studies indicated well-suspended, bimodal colloidal Cu NPs (70 150 and 5 10 nm) with extended air-stability up to 300 min and stable Cu NP films surfaces with 14% oxidation after 20 days. FTIR spectroscopy suggested that these capping agents were effectively adsorbed on the NP surface providing oxidation resistance in aqueous and dry conditions. Compared to previously reported Cu NP syntheses, this biological process substantially reduced the requirement for hazardous organic solvents and chemical reducing agents, while reducing the levels of Cu oxide impurities in the product. This process was highly reproducible and scalable from 0.01 to 1-L batches.
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  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. C
Additional Journal Information:
Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2050-7526
Royal Society of Chemistry
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); High Temperature Materials Laboratory (HTML)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States