Molecular weight effects of polyethylene glycol on the microstructure of metallic bismuth for electrochemical sensing of Sn2+

This investigation fabricates bismuth-film electrodes (BFEs) to replace mercury-film electrodes (MFEs) for heavy metal sensing because of the toxicity and damage of mercury to human health and environments. Electroplating is a simple route for effectively controlling the surface morphology and microstructure of metals/alloys. In this investigation, citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) serve as the complex agents meanwhile polyethylene glycol (PEG) serves as an adsorbate in the Bi(NO₃)₃ 5H₂O plating bath. Effects of the PEG molecular weight on the morphology and microstructure of BFEs are systematically compared in this work. Moreover, BFEs prepared from different plating conditions are evaluated for the application of Sn²⁺ sensing. The results reveal that the Sn(II) sensing ability strongly depends on the grain size but weakly depends on the intensity ratio of Bi(110)/Bi(012) facets because of a relatively large intensity ratio of Bi(110)/Bi(012) facets.