Oriented Attachment Is a Major Control Mechanism To Form Nail-like Mn-Doped ZnO Nanocrystals

Abstract

Here, we present a controlled synthesis of Mn-doped ZnO nanoparticles (NPs) with predominantly nail-like shapes, whose formation occurs via tip-to-base-oriented attachment of initially formed nanopyramids, followed by leveling of sharp edges that lead to smooth single-crystalline "nails". This shape is prevalent in noncoordinating solvents such as octadecene and octadecane. Yet, the double bond in the former promotes oriented attachment. By contrast, Mn-doped ZnO NP synthesis in a weakly coordinating solvent, benzyl ether, results in dendritic structures because of random attachment of initial NPs. Mn-doped ZnO NPs possess a hexagonal wurtzite structure, and in the majority of cases, the NP surface is enriched with Mn, indicating a migration of Mn ions to the NP surface during the NP formation. When the NP formation is carried out without the addition of octadecyl alcohol, which serves as a surfactant and a reaction initiator, large, concave pyramid dimers are formed whose attachment takes place via basal planes. UV-vis and photoluminescence spectra of these NPs confirm the utility of controlling the NP shape to tune electro-optical properties.

Experimental and Molecular Simulation Studies of the Attachment Behavior of Photoinitiator XBPO Crystals in Different Solvents

“…They demonstrated the critical role of the solvent in nanocrystal aggregation. The oriented aggregation of Mn-doped ZnO nanoparticles has been readily observed in the noncoordinating solvents rather than coordinating solvents . In our case, the above results have shown that the layer number and occurrence frequency of attachment vary in different solvents.…”

“…The oriented aggregation of Mn-doped ZnO nanoparticles has been readily observed in the noncoordinating solvents rather than coordinating solvents. 57 In our case, the above results have shown that the layer number and occurrence frequency of attachment vary in different solvents. Hence, a solvent-mediated growth mechanism is proposed for the attachment behavior of crystals, as illustrated in Figure 12.…”

“…The differences observed in the aggregates may be caused by the effects of the solvent. Patterson and his co-workers investigated Mn-doped ZnO nanoparticles with predominantly nail-like shapes whose formation was by tip-to-base-oriented attachment of initially formed nanopyramids. They found that this shape is prevalent in noncoordinating solvents (octadecene and octadecane) rather than coordinating solvents.…”

Anticorrosion Performance and Application of a Mixed-Valence Mn0xMn2+0.05–xZn0.95O Solid Solution Induced by Magnetic Doping

“…The plot of 5MZO showed the typical peak of Mn 2+ . 20,51 After the moderate introduction of N 2 H 4 •H 2 O in 5MZO-5 DMS, the average BE of Mn decreased where the maximum peak fell between Mn and Mn 2+ . When 10 mL of N 2 H 4 •H 2 O was added, the average BE of Mn in 5MZO-10 DMS shifted toward the higher-energy side compared with 5MZO-5 DMS, but it was still lower than that of 5MZO.…”

“…The introduction of mixed-valence Mn ions can change the oxidation state, growth kinetics, amount of oxygen vacancies, and electronic properties of the materials. Most research studies have focused on the preparation, origin of magnetism, and crystal structure. , The studies of mixed-valence Mn-doping materials in the field of supercapacitors, spintronic devices, batteries, and gas sensors remain in the phase of theoretical analysis. Further exploration of pragmatic applications and mechanisms is demanded.…”