Engineering the architectural diversity of heterogeneous metallic nanocrystals

Abstract

Similar to molecular engineering where structural diversity is used to create more property variations for application explorations, the architectural engineering of heterogeneous metallic nanocrystals (HMNCs) can likewise increase the versatility of metallic nanocrystals (NCs). Here we present a synthesis strategy capable of engineering the architectural diversity of HMNCs through rational and independent programming of every architecture-determining element, that is, the shape and size of the component NCs and their spatial arrangement. The strategy is based on the galvanic replacement reaction of a self-sustaining layer formed by underpotential deposition on a polyhedral NC. The selective deposition of satellite NCs on specific site of the central NC is realized by creating a geometry-dependent heterogeneous electron distribution. This site-selective deposition approach is applicable to central NCs in various polyhedral shapes and sizes. The satellite NCs can further develop their own shape and size through crystal growth kinetics control.

Metastability of anatase: size dependent and irreversible anatase-rutile phase transition in atomic-level precise titania

“…The nucleation model explains how the phase difference forms; still, it is unclear how the difference in the chemical conversion processes accelerates which of the kinetic or thermodynamic control nucleation. As the future works, although the importance of kinetics in nanocrystal growth has been discussed for the size distribution and shape control46474849, the simulation and correlating experiments to understand the factors for kinetic and thermodynamic control nucleation will be requirement to control the phase formation of nanocrystals, because of the complexity. The nucleation reactions are a complex system to give different crystal phases based on difference in the first reaction setup through multiple interactions40; for example, in a chemical system to synthesize nano-size TiO 2 , the nucleation correlates with strengthen in dehydration defined by the reaction condition and with multiple interactions between TiO 6 octahedral units, ligands of Ti precursors, anions, solvents, and/or additives.…”

Review—Conversion Coatings Based on Zirconium and/or Titanium

“…29,46,48,50,54,59,61,69,70,74,76,107 Some formulations contained more Ti, 50,59,69,70 whereas others contained more Zr. 48,60,74,76,127 Even when the ratio of Ti and Zr compounds in the bath was reported, it is difficult to find a relationship between their concentration in the bath and their content in the coating. When both compounds were present in the bath, both were also usually found in the coating 46,48,59,69,70 but not necessarily in the same ratio as in the bath.…”

“…81 The majority of Zr/Ti based conversion coatings are in the category of thin coatings, between 10 nm and 50-80 nm. 6,[32][33][34]44,49,52,76,77,88,90,91,97,102,105,106,108,112 Coatings with thickness between 100 nm and 600 nm were reported as well, 48,81,94,127 and even in the micrometer thickness range from 1.0 μm up to 6 μm. 30,37,43,59,61,80,119,127 Thickness is related to other parameters such as substrate, pH, time of immersion and stirring, as discussed in Conversion bath parameters and Effect of substrate on coating formation sections.…”

Tailoring self-organized nanostructured morphologies in kilometer-long polymer fiber

“…However, the current generation of nanoscale materials, such as nanowires and nanospheres, are not complex enough to serve as building blocks for the design of well-ordered and multifunctional systems analogous to these found in nature9. It is therefore necessary to devise engineering techniques1011 by which one can exercise a greater level of control over material properties, shapes, morphologies and assembly mechanisms that may facilitate the design of various devices with novel optical, mechanical, thermal and electrical properties1213141516.…”