Role of surfactants: One step facile synthesis of hetero structured Ag-Ni alloy by seed less approach
2018
Alruqi, Sarah Saad | Al-Thabaiti, Shaeel Ahmad | Malik, Maqsood Ahmed | Khan, Zaheer
Surfactant assisted seedless synthesis of Ag-Ni alloy nanoparticles were carried out in an one step process by co- reduction of mixed metal salts (AgNO₃ + Ni(NO₃)₂) solutions using ascorbic acid as reducing agent. To explore the role of surfactant, two types of surfactants were studied; cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecylbenzenesulphonate (SDBS). The surface plasmon resonance peak (SPR) of CTAB capped Ag-Ni and SDBS capped Ag-Ni located at 450 nm and 410 nm wavelengths, respectively. For SDBS, visual observations and time resolved spectra indicates that the reaction mixture containing different mixing orders of reactants (SDBS + Ag⁺ + Ni²⁺ + ascorbic acid and SDBS + Ni²⁺ + Ag⁺ + ascorbic acid) have different colours as well as different SPR band positions with time. Presence of SDBS delayed the nucleation processes. The Ag-Ni alloy with both surfactants shows that the a red shift to ca. 410 nm and 450 nm with respect to the SPR of AgNPs. The absence of SPR bands at ca. 375 nm and 500–700 nm ruled out the possibility to the formation and /or deposition NiO + Ni(OH)₂ on the surface of Ag-Ni alloy. The average number of Ag-Ni atoms per nanoparticle, molar concentration of Ag-Ni and free energies (surface, volume and excess energy due to mixing) were calculated and discussed. The Ag-Ni alloy used as a catalyst to the photo-assisted degradation methyl orange and showed a higher photo catalytic activity. The synthetic method reported here suggests a very promising use of the suitable stabilizer for the preparation of an alloy nanoparticles having different optical properties, which is a subject of immense interest.
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