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Mn Oxide‐Silver Composite Nanowires for Improved Thermal Stability, SERS and Electrical Conductivity
Author(s) -
Pradhan Mukul,
Sinha Arun Kumar,
Pal Tarasankar
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201304518
Subject(s) - materials science , composite number , nanowire , raman scattering , nanocomposite , raman spectroscopy , annealing (glass) , oxide , chemical engineering , thermal stability , electrical resistivity and conductivity , nanoparticle , aqueous solution , nanotechnology , composite material , metallurgy , chemistry , physics , electrical engineering , engineering , optics
Redox transformation reaction between aqueous AgNO 3 and Mn(CH 3 COO) 2 at low temperature (∼80 °C) has been adopted for industrial‐scale production of uniform Ag–MnOOH composite nanowires for the first time. Varying amounts of incorporated Ag in the composite retain the 1D morphology of the composite. Nanowires upon annealing evolve Ag–MnO 2 nanocomposites, once again with the retention of the parental morphology. Just 4 % of silver incorporation in the composite demonstrates metal‐like conducting performance from the corresponding semiconducting material. Transition of MnO 2 to Mn 2 O 3 to Mn 3 O 4 takes place upon heat treatment in relation to successive increase in Ag concentrations in the nanowires. The composites offer resistance to the observed oxide transformation. This is evidenced from the progressive increase in transition temperature. In situ Raman, ex situ thermal and XRD analysis corroborate the fact. The composite with 12 % Ag offers resistance to the transformation of MnO 2 , which is also verified from laser heating. Importantly, Ag nanoparticle incorporation is proved to offer a thermally stable and better surface enhanced Raman scattering (SERS) platform than the individual components. Both the Ag–MnOOH and Ag–MnO 2 nanocomposites with 8 atomic % Ag show the best SERS enhancement (enhancement factor ∼10 10 ). The observed enhancement relates to charge transfer as well as electromagnetic effects.