Sulfur Precursor Reactivity Affecting the Crystal Phase and Morphology of Cu2-x S Nanoparticles.

For plasmonic copper-deficient Cu2-x S nanoparticles (NPs), accurate control of the crystal phase and morphology is highly desirable as both of which are known to determine the localized surface plasmon resonance (LSPR) wavelength and amplitude. Here, how the sulfur precursor reactivity in the synthesis of Cu2-x S NPs affects the resulting crystal phase and morphology is examined. Djurleite Cu1.94 S, roxbyite Cu1.8 S, digenite Cu1.8 S as well as covellite CuS nanodisks were synthesized by using 1-dodecanethiol, N,N-dibutylthiourea, and crystal sulfur 1-octadecene/oleylamine solutions and their crystal phase dependent LSPR properties were exhaustively discussed. In addition, crystal phase interconversion between covellite CuS and djurleite/roxbyite Cu2-x S was realized in the presence of the above sulfur precursors. On the other hand, djurleite Cu1.94 S nanorods rather than nanodisks were prepared by replacing 1-dodecanethiol with more reactive tert-dodecanethiol. The structural and morphological Cu2-x S NPs here holds great promise in the application of photothermal therapy, photocatalysis, surface-enhanced Raman scattering (SERS), and many others.