Nonconvex Morphology of Metallic Copper Obtained via Nonclassical Crystallization of Copper Hydride

Abstract

Copper particles with a desert rose morphology and high surface area were obtained via decomposition of a copper hydride whose particles possesses a similar shape. Copper hydride was synthesized by the reaction between copper sulfate and hypophosphorous acid at 50 °C. The different reaction steps of the copper hydride formation were monitored by two time-dependent techniques: in situ photon cross-correlation spectroscopy and ex -situ transmission electron microscopy. At the initial stage of the reaction, emulsion droplets of a particular size were formed, followed by the growth and agglomeration of copper hydride crystallites in the confinement of these droplets. The final structure consists of rose-like shaped particles with an average size of about 217 ± 53 nm arranged into chains. The surface area of these particles was estimated to be 41 ± 8 m2/g. The nucleation and growth of the copper hydride occur via a nonclassical crystallization pathway.

Non-classical crystallization of CeO2 by means of in situ electron microscopy

“…Generally, the size of transformed intermediate gel-like phase in solution determines the size of the formed aggregates. 31,32 Our result suggests that these sizes of aggregates are not influenced by the different applied dose rates and therefore by radical concentrations.…”

Radiation Chemistry Provides Nanoscopic Insights into the Role of Intermediate Phases in CeO2 Mesocrystal Formation

“…Non‐classical crystallization occurs via the formation of a sequence of metastable phases of increasing density. [ 19 , 20 , 21 , 22 ] Such sequential precipitation is often preferable since it requires to overcome smaller activation energy barriers as compared to the one‐step crystallization route explained by Oswald ripening in the classical theory. [ 23 , 24 ] Although the general non‐classical crystallization pathway proposed a while ago,[ 19 , 20 ] describes the formation of mesocrystals, empirical evidence is still required to verify the particular stages of growth (e.g.…”

“…Formation of mesocrystals is an example of a non‐classical crystallization pathway. Non‐classical crystallization occurs via the formation of a sequence of metastable phases of increasing density [19–22] . Such sequential precipitation is often preferable since it requires to overcome smaller activation energy barriers as compared to the one‐step crystallization route explained by Oswald ripening in the classical theory [23, 24] .…”

“…[18] Formation of mesocrystals is an example of an on-classical crystallization pathway.N onclassical crystallization occurs via the formation of asequence of metastable phases of increasing density. [19][20][21][22] Such sequential precipitation is often preferable since it requires to overcome smaller activation energy barriers as compared to the one-step crystallization route explained by Oswald ripening in the classical theory. [23,24] Although the general non-classical crystallization pathway proposed aw hile ago, [19,20] describes the formation of mesocrystals,e mpirical evidence is still required to verify the particular stages of growth (e.g.m echanism of three-dimensional mutual alignment of the nanoparticles and the role of intermediates) as well as the individual features in the formation of as pecific compound.…”