Interplay Between Size and Crystal Structure of Molybdenum Dioxide Nanoparticles—Synthesis, Growth Mechanism, and Electrochemical Performance

Abstract

A detailed study is presented on the formation of MoO(2) nanoparticles from the dissolution of the precursor to the final rodlike product, with a focus on the exploration of the inorganic reaction occurring ahead of the nucleation step, and interplay between size and crystal structure of MoO(2). In situ X-ray absorption spectroscopy experiments show that the crystallization and the growth process of MoO(2) nanorods is initiated by rapid reduction of the MoO(2) Cl(2) precursor in benzyl alcohol and acetophenone. This reaction triggers the nucleation of 2 nm MoO(2) particles with spherical shape and hexagonal crystal structure. The transformation from spheres into rods emerges as a complex process driven by oriented attachment. High-resolution transmission electron microscopy and X-ray diffraction results provide evidence that the 2 nm particles first aggregate into 5-20 nm-large oriented assemblies. The increase in particle size induces the phase transition from hexagonal to the less symmetrical monoclinic crystal structure, and finally the transformation into rods. Is it shown that electrodes for lithium-ion batteries based on MoO(2) nanorods have a long-term cycling life. The specific discharge capacity even after 200 cycles at a discharge rate of 1 C is about 300 Ah kg(-1) .

Self-assembled porous MoO2/graphene microspheres towards high performance anodes for lithium ion batteries

“…The diffraction peaks of as-prepared composite and SA-MGH microspheres are assigned to pure monoclinic MoO 2 phase (JCPDS: 65e5787) of P21/c (no.14) space group as shown in Fig. 3a [20]. The well resolved diffraction peak of SA-MGH microsphere indicates the formation of highly crystalline hybrid structure.…”

“…Numerous electrode designs have emerged to mitigate the adverse mechanical effects and improve the overall electrochemical performance of MoO 2 based anodes. Recently, MoO 2 nanostructures such as ordered mesoporous material [19], nanoparticles [20], nanocrystals [21], nanosheets [22], and nanorods [23], and MoO 2 /carbon hybrid composites such as MoO 2 /carbon nanotube [24], MoO 2 /carbon [25], and MoO 2 /graphene [26] have been investigated as LIB anodes to hold the promise for better electrochemical performance than bulk counterparts. On the other hand, it is a great challenge to synthesize nanomaterials of hierarchical architectures and multi functionalities, or hybrid combinations of various nanomaterials to fulfil the on-board energy demands.…”

Study of the Chemical Mechanism Involved in the Formation of Tungstite in Benzyl Alcohol by the Advanced QEXAFS Technique

“…[10] For fast dynamic processes, in situ extended X-ray absorption fine structure spectroscopy (EXAFS) or quick-EXAFS [11] (QEXAFS), based on rapid scanning with a continuously moving monochromator, has proven to be successful in, for example, catalysis research, [10a, 12] particle growth studies [13] and the investigation of the chemical reaction mechanisms involved in the formation of nanoparticles. [14] The reaction between WCl 6 and benzyl alcohol was established several years ago for the synthesis of tungstite platelets. [15] Since then, this approach has continuously been exAbstract: Insight into the complex chemical mechanism for the formation of tungstite nanoparticles obtained by the reaction of tungsten hexachloride with benzyl alcohol is presented herein.…”

Systematic study on the influence of the morphology of α-MoO3 in the selective oxidation of propylene

“…Especially selective oxidation reactions are known to be structure sensitive and thus strongly dependent on the shape [6][7][8][9]. Therefore the ability to control particle size, shape and composition of transition metal oxides has become an important research topic [10][11][12][13].…”