(244e) The Role of Iodide in the Solution-Phase Growth of Cu Microplates: A Multi-Scale Theoretical Analysis from First Principles

The capability to synthesize well-defined metal nanostructures is immensely beneficial to energy technologies involving catalysis and electronics. Despite the significant contribution of halides in obtaining well-defined metal nanostructure in solution-phase syntheses, the mechanisms by which they function are poorly understood. In this study, we use first-principles density functional theory (DFT) to define the role of iodide in the solution-phase growth of Cu microplates. First, we found that the presence of iodide allows a stronger binding and slower diffusion of Cu atom on Cu(100) compared to Cu(111). Moreover, Cu adatoms bind more strongly to hcp hollow sites than fcc hollow sites on Cu(111) upon the adsorption of iodide, which could promote the formation of stacking faults, essential for growing plate-like Cu nanostructures. These features promote a preferential accumulation of Cu atoms on the {100} side facets of a plate, and thus lateral two-dimensional (2D) growth. To relate our findings to Cu plate growth observed in experiments, a case study using magnetic spheres was conducted, in which we discovered why various shapes of the plates were observed during the growth in experiment and also found that two or more stacking faults are necessary for a continuous lateral plate growth. Finally, we incorporated our calculated DFT energy barriers into the Absorbing Markov Chain calculations to study the propensity for 2D kinetic growth of Cu plates in the presence of iodide. Our kinetic model predicts that Cu plates can reach several microns in width at experimental temperatures, consistent with experiments.