Pre-plating of Bismuth film electrode with coexisted Sn2+ in electrolyte

•A flat and compact BiFSn-0.3V was electro-deposited with Sn2+ coexisted in electrolyte.•Sn2+ affected the formation of the metal ion deficient layer in plating process.•BiFSn-0.3V has improved working window and reproducibility compared with BiFE.

Bismuth film electrodes (BiFEs) have extensive application in electrochemical analysis, while the sensitivity and repeatability are greatly related with the morphology of the deposited bismuth film. In this study, a flat and compact bismuth film on GC electrode was obtained by electro-plating in a electrolyte containing Bi3+ and Sn2+, but no Sn element was found in the obtained film owing to the deposition potential more positive than ESn2+/Sn. The contribution of Sn2+ to the change in the morphology of bismuth film was explained that the coexisted Sn2+ ions in the electrolyte blocked the migration of Bi3+ ions during the deposition since Sn2+ ions could not be deposited under such conditions, then the thickness of metal ion deficient layer (MIDL) near the substrate was weakened, allowing more flat and compact bismuth film grown. The resulted BiFE has broader working window and improved repeatability than BiFE with dendritic Bi film.

Graphical abstractA flat and compact Bismuth film was electro-deposited in electrolyte coexisted with Sn2+, but no Sn element was co-deposited by controlling the deposition potential. The Sn2+ changed the structure of metal ion deficient layer (MIDL) during the plating procedure, resulting in more chance for Bi atoms to grow homogeneously. The flat morphology and no co-deposited Sn element made the BiFE wide working window and excellent repeatability.Figure optionsDownload full-size imageDownload as PowerPoint slide