A study on the key factors affecting the sensibility of bismuth deposits toward Sn2+: Effects of bismuth microstructures on the Sn2+ pre-deposition

The pre-deposition of Sn following with the square-wave anodic stripping voltammetric (SWASV) analysis is employed to determine the Sn2+-sensing ability of bismuth-film electrodes (BFEs). The influences of Bi microstructures, such as grain size, preferred orientation ratio between Bi(1 1 0) and Bi(0 1 2) (denoted as f), and average roughness factor (Ra) of Bi deposits on the Sn2+-sensing ability, are investigated. The preferred orientation ratio is a key factor determining the Sn2+-sensing ability of BFEs meanwhile a synergistic effect between grain size and f on enhancing the current density of Sn2+ sensing is obtained when f is above 0.11. The crystalline facet of Bi(1 1 0) favorable for pre-depositing Sn is the main reason enhancing the Sn2+ sensing of Bi deposits. Thus, this work shows that Sn2+ sensing through stripping of pre-deposited Sn on BFEs does not follow the mechanism of forming Bi-alloy amalgams since the successful pre-deposition of trace Sn2+ on Bi strongly depends on the effective exposure of crystalline facet of Bi(1 1 0).