Chloroantimonate electrochemistry in dichloromethane

Abstract

Antimony is a technologically relevant element, which is present in many semiconductor materials. Electrodeposition of such materials offers a potential route for cheaper and less wasteful manufacturing, and is especially suited for micro- and nano-feature sizes with complex geometries. Previous work has shown the applicability of electrodeposition of p-block metals and metalloids from the weakly coordinating solvent dichloromethane, using halometallate precursors. Here we more thoroughly investigate the behaviour of the tetrabutylammonium chloroantimonate precursor, [TBA][SbCl4]. We use voltammetry at a stationary macroelectrode, rotating disc electrode and electrochemical quartz crystal microbalance, as well as microelectrodes and highlight the advantages of microelectrodes in this context. Using [TBA]Cl as a background electrolyte it is found that the diffusion coefficients calculated from the rotating disc electrode and microelectrodes are similar. Due to the possibility of mixed speciation with an excess of Cl−, tetrabutylammonium tetrafluoroborate, [TBA][TFB], is also used as a background electrolyte and it is found that the diffusion coefficient does not change. Using a modified form of the Stokes-Einstein equation, that takes into account the shape of the solute and the relative sizes of the solute and solvent, the diffusion coefficients of the antimony precursor and decamethylferrocene are consistent with their relative sizes. Electrodeposition onto large surface area platinum and titanium nitride substrates using either background electrolyte results in amorphous deposits of elemental antimony with similar morphology.