The effects of colorimetric detection of heavy metal ions based on Au nanoparticles (NPs): size and shape—a case of Co2+

The different sized and shaped Au NPs have intrigued considerable attention, because they possess different surface plasma resonance (SPR) absorption bands and thus result in many colorimetric Au NP-based detection applications. In this article, four different sized and shaped Au NPs of nanodots/rods were prepared and characterized. The as-prepared Au NPs were modified by the negatively charged anions of [SCH 2 CO 2 ] 2− to investigate both the size and shape effects of modified Au NPs on colorimetric detection of Co 2+ and the corresponding SPR absorption properties. The different-shaped Au NPs possess different SPR absorption properties. The Au nanorods appeared to be colorimetric sensitive for Co 2+ sensing.