Evidence of Induced Underpotential Deposition of Crystalline Copper Antimonide via Instantaneous Nucleation

Abstract

was electrodeposited onto transmission electron microscopy (TEM) grids to investigate changes in morphology, composition, and crystal structure during the early stages of nucleation and growth. Multiple transitions were observed within the first second of the deposition, leading to the formation of crystalline . These transitions were analyzed using TEM, scanning electron microscopy, selected area electron diffraction, and energy-dispersive X-ray spectroscopy. The nucleation sites are initially polycrystalline antimony with amorphous copper, which then transition through a polycrystalline copper intermediate containing some antimony before forming crystalline . These analyses provide direct evidence that does not deposit directly from solution but deposits by induced underpotential deposition. This is indicative of the electrodeposition of a typical alloy initially, but what is unusual is that the deposit at longer time scales is a highly crystalline intermetallic. This investigation is unique because TEM grids allow the interface between the deposited material and the substrate to be investigated. This is possible because the composite carbon film on the TEM grid behaves as a transparent substrate. This approach can be extended to other systems, allowing the development of a comprehensive understanding of the electrodeposition of intermetallic compounds.