FeCo nanoalloy formation by decomposition of their carbonyl precursors

Abstract

In this paper we describe the synthesis of iron and cobalt nanoalloys by the co-decomposition of iron and cobalt carbonyl precursors in the presence of polystyrene as a surface stabilizing agent. In order to prevent the preferential aggregation of metal atoms in the iron-cobalt nanoalloys, which results in phase segregation, the decomposition kinetics of the Fe(CO) 5 and Co 2 (CO) 8 precursors had to be firmly established and controlled. The kinetics of cobalt cluster formation have been thoroughly investigated and documented, but data for Fe(CO) 5 decomposition are relatively scarce. To fully explore the kinetic characteristics of the formation of iron nanoclusters, initial Fe(CO) 5 concentrations and reaction media solvents were varied and hence reaction order and rate constants were established. Our results suggest that this decomposition is a higher-order process (not first-order as previously assumed), with a complicated intermediate mechanism, which has been postulated and experimentally verified. By using this kinetic data, we were able to predict the necessary conditions for the in situ creation of new iron-cobalt nanoalloys using carbonyl precursors. Equal initial concentrations of both precursors generated nanoalloys with a crystalline core-shell dense morphology, while precursor concentrations corresponding to initial equal rates of decomposition generated polycrystalline nanoalloys with a diffuse morphology.

On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

“…Since the control of metal distribution in a bimetal nanostructure is crucial to the enhancement of catalysts performance, many efforts are being devoted to study innovative techniques to obtain different bimetallic nanostructures, including multistep synthesis [61], electrochemical dealloying [6,[39][40][41], impregnation [7,48], chemical reduction [49,50], thermal decomposition [62], electrochemical synthesis [3,63,64], microwave synthesis [65,66] and synthesis in microemulsions [30], as summarized in various reviews [2,50,51].…”

Synthesis of iron oxide nanorods and nanocubes in an imidazolium ionic liquid

“…To be specific, we examined the particle formation for the mixture of Fe(CO) 5 5 , which were centered at 2019 and 1996 cm −1 in the typical hydrocarbon solvents [45], moved to 2021 and 2000 cm −1 , respectively. These shifts were due to the interaction between the [BMIM] cation and the carbonyl groups of Fe(CO) 5 [46].…”

Grafting and Thermal Stripping of Organo‐Bimetallic Clusters on Au Surfaces: Toward Controlled Co/Ru Aggregates

“…This concept is well known in ultra-high-vacuum (UHV) surface physics, in which evaporator calibration is often a cumbersome task. With the exception of silver and gold nanoalloys, [10] transition-metal nanoalloys have been synthesized only in very limited cases, [11,12] and mixtures of monometallic, carbonyl complexes have typically been used, [13,14] which renders precise control of their composition more difficult than if bimetallic single-source precursors were used. Therefore, new strategies are desirable and the present approach is based on recent advances in both coordination chemistry and surface physics for the fabrication of self-organized bimetallic clusters on surfaces.…”