Synthesis of 16-Mercaptohexadecanoic acid capped gold nanoparticles and their immobilization on a substrate

Controlled assembly of nanoparticles on substrates is a promising path to develop miniaturized electronic and optical devices. Among the important issues to be addressed in this area include immobilization of the nanoparticles on substrates in order to ensure that the system is robust. In this work, 16-mercaptohexadecanoic acid (16-MHDA) capped gold nanoparticles with a narrow size distribution have been synthesized through a single phase synthesis method and subsequently immobilized on to silicon surface through covalent molecular assembly. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the absence of unreacted thiol in the synthesized gold nanoparticles. Presence of gold nanoparticles on Si surface after the immobilization process was confirmed through XPS. Cross-sectional high resolution transmission electron microscopy (HR-TEM) images provide direct evidence that the particles are indeed anchored to the silicon surface. The formation of uniform-sized and separated acid functionalized gold nanoparticles and their immobilization on to Si provide a basis for further nano-structuring.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of well-separated and uniform sized 16-MHDA capped AuNPs ► Covalent immobilization of such AuNPs on a Si substrate without aggregation ► Direct evidence for covalently anchored AuNPs through cross-sectional HR-TEM