Effects of polyethylene glycol and gelatin on the crystal size, morphology, and Sn2+-sensing ability of bismuth deposits

The influences of citric acid (CA), ethylenediaminetetraacetic acid (EDTA), polyethylene glycol (PEG), and gelatin on the deposition behavior of Bi were systematically investigated through the linear sweep voltammetric (LSV) analysis. Based on the LSV results, deposits plated from a typical solution containing 0.05 M Bi(NO3)3·5H2O and various combinations of complex agents and additives with pH = 3.5 at 1 and 30 mA cm−2 were characterized by scanning electron microscopic (SEM) and X-ray diffraction (XRD) analyses. The adhesion of deposits and the formation of dendrites were respectively improved and inhibited by the adsorption of PEG onto Bi deposits. With adding the above four compounds, a synergistic effect was shown to reach a nano-sized, sphere-like, porous morphology of a Bi deposit at 30 mA cm−2. The crystal size and morphology of Bi deposits were found to affect the sensing ability of Sn2+ through the square-wave anodic stripping voltammetric (SWASV) analysis.