The Effect of Electrodeposition Parameters and Morphology on the Performance of Au Nanostructures for the Detection of As (III)

A series of Au nanospikes and dendrites were electrodeposited with either an inorganic (Pb2+) or organic (cysteine) growth directing agent for different times to obtain varied morphology. These structureswere comparedwith gold nanoparticles of three different shapes (Octahedral, Cubic and Rhombic Dodecahedral) for detection of As (III) by SquareWave Anodic Stripping Voltammetry (SWASV). The sensitivity and limit of detection (LOD) was dependent on the surface crystallographic orientations and the morphology, with superior sensitivity confirmed with a maximum amount of Au (111) facets on the surface for the nanoparticles. XRD studies suggested that the shape directing influence of Pb2+is lost on the gold nanospikes at higher deposition time, and that the size of the (111) terraces on the polycrystalline surfaces decreased, which led to a loss of performance. For gold dendrites, as the cysteine maintained shape directing behavior through hierarchical dendritic branching, deposition time did not affect the sensitivity. The study confirms that electrodeposition parameters or nanoparticle synthesis methods for Au surfaces in arsenic sensing needs to be carefully controlled, to either maximize the (111) facets, or minimize the steps on a polycrystalline Au surface, and that inorganic and organic shape directing agents will have differing effects.