A general synthetic method based on a solvothermal route for the preparation of multiple transition metal oxide (MTMO) mesoporous nanospheres (ZnaNibMncCodFe2O4, 0 ≤ a, b, c, d ≤ 1, a + b + c + d = 1) with controllable composition and uniform size distribution has been developed. The as-prepared ZnaNibMncCodFe2O4 nanospheres are formed by self-assembly of nanocrystals with the size of 5–10 nm via structure-directing agents and mineralizer coordinating effect as well as optimization of the synthesis conditions. It has been identified that the addition of mineralizer is crucial for the control of the nucleation process when the metallic precursors are reduced; meanwhile the structure-directing agent is key to forming the mesoporous structure. A number of characterization techniques including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, temperature-programmed reduction, and nitrogen adsorption have been used to characterize the as-prepared mesoporous products. The overall strategy in this work extends the controllable fabrication of high-quality MTMO mesoporous nanospheres with designed components and compositions, rendering these nanospheres with promising potential for various applications (oxygen reduction reaction, magnetic performance, supercapacitor, lithium-ion batteries, and catalysis).

We report in situ growth of mesoporous Mn0.5Co0.5Fe2O4 (MCFO) nanospheres on graphene to form MCFO/graphene nanocomposites by a facile solvothermal method. In the synthesis, Mn(CH3COO)2, Co(CH3COO)2, and FeCl3 were used as the metal precursors and CH3COOK, CH3COOC2H5, and HOCH2CH2OH as the mixed solvent. The obtained MCFO nanospheres (50–200 nm) were composed of small nanoparticles (5–15 nm), and the graphene surface acted as the nucleation sites in growing MCFO nanospheres. Compared with the bare MCFO nanospheres and the MCFO nanospheres physically mixed with graphene, the MCFO/graphene nanocomposite with 2.1 wt % graphene as anode material in Li ion batteries showed a significantly enhanced electrochemical performance with high lithium storage capacity and excellent cycling stability. This is because the introduced graphene can prevent the aggregation of nanospheres and provides a pathway for excellent Li+ ion diffusion and electronic conduction. This work opens a way for facile fabrication of metal oxide/graphene nanocomposites.

A general synthetic method based on a solvothermal route for the preparation of multiple transition metal oxide (MTMO) mesoporous nanospheres (ZnaNibMncCodFe2O4, 0 ≤ a, b, c, d ≤ 1, a + b + c + d = 1) with controllable composition and uniform size distribution has been developed. The as-prepared ZnaNibMncCodFe2O4 nanospheres are formed by self-assembly of nanocrystals with the size of 5–10 nm via structure-directing agents and mineralizer coordinating effect as well as optimization of the synthesis conditions. It has been identified that the addition of mineralizer is crucial for the control of the nucleation process when the metallic precursors are reduced; meanwhile the structure-directing agent is key to forming the mesoporous structure. A number of characterization techniques including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, temperature-programmed reduction, and nitrogen adsorption have been used to characterize the as-prepared mesoporous products. The overall strategy in this work extends the controllable fabrication of high-quality MTMO mesoporous nanospheres with designed components and compositions, rendering these nanospheres with promising potential for various applications (oxygen reduction reaction, magnetic performance, supercapacitor, lithium-ion batteries, and catalysis).