Growth Kinetics of Metal Nanowires and Nanoplates

Metal nanocrystals have gained tremendous attention due to their superior performance in various applications, ranging from selective catalysis to electronic devices to plasmonic applications. For these and many other applications, the properties of the nanocrystals are highly sensitive to their shape. However, it remains a challenge to achieve high shape selectivity in solution-phase syntheses. I will discuss our efforts to understand the growth of Cu and Ag nanocubes, nanowires and nanoplates, which is facilitated by the inclusion of halide ions (chloride, bromide, and iodide) in the synthesis protocol. We use ab initio thermodynamics based on quantum density-functional theory (DFT) to demonstrate how these halides create thermodynamic driving forces for cubes, plates and wires, by selectively altering surface energies. Using a combination of DFT and the theory of absorbing Markov chains, we demonstrate how halides affect surface diffusion and interfacet transport to drive the growth of particular nanoshapes in the presence of halide. Our results agree with experiment and indicate a promising way to exact control over nanocrystal synthesis.