Hierarchically Structured Cobalt Oxide (Co₃O₄):  The Morphology Control and Its Potential in Sensors

Abstract

A polyol process was developed to synthesize Co3O4 with controllable superstructures. By tuning the reaction conditions, the prepared Co3O4 were readily regulated in its morphologies, which could vary from nanosphere to two-dimensional (2D) nanoplates and 3D hierarchical structures, and finally to microspheres. The growth kinetics of such a process was also studied. The synthesized Co3O4 exhibited good sensitivity, remarkable selectivity, and high stability as an alcohol sensor material.

Direct Hydrothermal Synthesis of Size-Controlled Co₃O₄ Nanocubes under Highly Condensed Conditions

“…[1][2][3][4][5] Especially, tricobalt tetraoxide (Co 3 O 4 ), a mixed-valence transition metal oxide with spinel crystal structure, is regarded as one of the most promising p-type semiconducting materials for industrial and scienti c applications such as heterogeneous catalysts, [6][7][8][9][10][11][12] solid-state sensors, [13][14][15] magnetic materials, 16,17) and lithium ion rechargeable batteries. [18][19][20][21] Up to date, various types of preparation methods have been developed for the preparation of Co 3 O 4 by thermal decomposition, [6][7][8]20,22,23) chemical spray pyrolysis, 24) spattering, 25) and sol-gel process.…”

Enhanced magnetic response of fluids using self-assembled petal-like iron oxide particles

“…This EG mediated method has been widely used to produce particles with controlled morphologies such V 2 O 5 hollow microspheres, SnO nanowires, cobalt alkoxide layered particles and flowerlike iron oxide particles. [9][10][11][12] Selfassembled iron oxide particles with nanometer size surface features were synthesized using high purity Fe͑NO͒ 3 ·6H 2 O, urea, and ethylene glycol.…”

Effect of anions on the morphology of Co3O4 nanostructures grown by hydrothermal method and their pH sensing application

“…Co3O4 nanostructures are expected to show even more excellent and tunable properties due to their versatile morphologies and structures. So far, many interesting nanostructures of Co3O4, including nanowires/nanorods [16,17], nanotubes [18,19], nanocubes [20][21][22], nanospheres [23][24][25], nanoplates [26] and nanowalls [27], have been prepared by using different growth methods. He et al synthesized Co3O4nanocrystals by a solubility controlled method using surfactant [28].…”

“…Co3O4 nanocrystals have also been synthesized via a facile combustion method by Feng et al [29]. Beside these several other methods have also been used for the synthesis of spinel Co3O4 nanocrystals such as sol-gel method, polyol process, solvothermal synthesis, polymer assisted synthesis, thermal decompositions, reflux/microwave assisted methods and hydrothermal synthesis for Co3O4 nanorods [30,23,[31][32][33][34][35][36]. All these methods produce high quality nanostructure with different morphologies, but the requirement of high temperature limits the compatibility of growth e.g.…”