Mild and facile synthesis of Ag2S nanowire precursor using mercaptoacetic acid as a reductant/stabilizer and its subsequent conversion to Ag2S or CdS nanowires

Silver sulfide nanowire precursor was prepared at room temperature by simple mixing of mercaptoacetic acid (MAA) and silver nitrate solutions for 10–20 min duration. The MAA concentration in the chemical reaction bath was varied from 1 to 10 mM to afford nanowire precursors ranging in length from 800 nm to 42 μm and diameters ranging from 53 to 210 nm. The chemical identity of the precursor was established as a Ag⁺–⁻SCH₂COOH complex by a variety of spectroscopic probes. It could be converted into crystalline Ag₂S nanowires (with no alteration in nanowire dimensions) by a thermal anneal at ∼300 °C. Reverse cation exchange of the Ag₂S nanowire precursor in a Cd²⁺-containing medium afforded CdS nanowires (with some alterations in morphology) whose chemical identity was confirmed by Raman spectroscopy and photoluminescence. Finally the dual role of MAA as a capping agent and reducing agent in the formation of the Ag₂S nanowire precursor complex is briefly discussed.