Influence of the injection temperature on the size of Ni-Pt polyhedral nanoparticles synthesized by the hot-injection me
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Research Letter
Influence of the injection temperature on the size of Ni–Pt polyhedral nanoparticles synthesized by the hot-injection method J.L. Reyes-Rodríguez, A. Velázquez-Osorio, and O. Solorza-Feria, Departamento de Química, Centro de Investigación y de Estudios Avanzados del I.P.N. CINVESTAV. Av. I.P.N. 2508, Col. Zacatenco, Delegación Gustavo A. Madero, C.P. 07360, Ciudad de México, México D. Bahena-Uribe and J. Roque, Laboratorio Avanzado de Nanoscopía Electrónica (LANE), CINVESTAV, Av. I.P.N. 2508, Col. Zacatenco, Delegación Gustavo A. Madero, C.P. 07360, Ciudad de México, México Address all correspondence to J.L. Reyes-Rodríguez at [email protected] (Received 11 July 2017; accepted 13 October 2017)
Abstract Ni–Pt polyhedral nanoparticles were synthesized through a thermochemical route by the hot-injection method using Oleylamine (Oam) and Oleic acid (Oac) solvents as simultaneous stabilizing and reducing agents. Several syntheses were performed to study the effect of the hotinjection temperature on nanoparticle size distribution. Results revealed that the injection of precursors in a mixture of Oam and Oac at 180 °C produced paramagnetic nanoparticles with an approximate size of 27 nm; these particles have uniformly defined polyhedral structures and show greater Pt accumulation on the edges and corners. Ni–Pt polyhedral nanoparticles with larger sizes and high polydispersity were obtained as the injection temperature was increased closer to the reduction temperature.
Introduction Modern advances in materials science have allowed the creation of the new generation of synthetic nanomaterials whose special properties have caught the attention of the scientific community. The current trend is to find strategies to control the size and morphology of the nanoparticles during their synthesis to obtain a specific orientation and preferential growth. This is widely illustrated in literature, as in the synthesis of Ag-based nanoprisms and octahedral particles;[1] hexagonal Co nanoplates;[2] Au double-walled nanoboxes;[3] metal oxide nanorods;[4] perfect metallic nanocubes;[5] Ni–Pt octahedral nanoparticles,[6,7] nanopolyhedra, and their evolution into nanoframes,[8–12] etc. Beyond their aesthetic beauty, these nanoforms possess special electronic and geometric properties intrinsically related to their superficial atomic arrangement. The physicochemical mechanism that gives rise to nanoparticles with a specific crystallographic orientation and characteristic shape is not yet fully understood. However, theoretical studies based on computational thermodynamic models constitute an adequate approach to predict nanoparticle properties and phase diagrams for different materials and alloys.[13,14] There is also evidence that the use of capping agents (also called as surfactants or stabilizing agents) such as Oleylamine (Oam) and Oleic acid (Oac) are the key to obtain ‘nanoforms’, as these compounds can selectively adhere to certain atoms of the nanoparticle seeds during their formative stage; thus ensuring, a slow growth rat
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