Multiple transition metal oxide mesoporous nanospheres with controllable composition for lithium storage

Abstract

A general synthetic method based on a solvothermal route for the preparation of multiple transition metal oxide (MTMO) mesoporous nanospheres (Zn_aNi_bMn_cCo_dFe₂O₄, 0 ≤ a, b, c, d ≤ 1, a + b + c + d = 1) with controllable composition and uniform size distribution has been developed. The as-prepared Zn_aNi_bMn_cCo_dFe₂O₄ 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).