Transition metal cobalt (Co) nanoparticle was designed as catalyst to promote the conversion reaction of Sn to SnO2 during the delithiation process which is deemed as an irreversible reaction. The designed nanocomposite, named as SnO2/Co3O4/reduced-graphene-oxide (rGO), was synthesized by a simple two-step method composed of hydrothermal (1(st) step) and solvothermal (2(nd) step) synthesis proc...

Cobalt oxide that has high energy density, is the next-generation candidate as the anode material for LIBs. However, the practical use of Co3O4 as anode material has been hindered by limitations, especially, low electrical conductivity and pulverization from large volume change upon cycling. These features lead to hindrance to its electrochemical properties for lithium-ion batteries. To improve...

In this report, functional one-dimensional (1-D) Pt-Co3O4 heterostructures with enhanced electrochemical properties were synthesized via colloidal polymerization of polymer-coated ferromagnetic cobalt nanoparticles (PS-CoNPs). Colloidal polymerization of dipolar nanoparticles into hollow metal-semiconductor nanowires was achieved via a consecutive galvanic replacement reaction between Co and Pt...

Semiconductor-based gas sensors that use n-type WO3 or p-type Co3O4 powder were fabricated and their gas sensing properties toward NO2 or NO (0.5-5 ppm in air) were investigated at 100 °C or 200 °C. The resistance of the WO3-based sensor increased on exposure to NO2 and NO. On the other hand, the resistance of the Co3O4-based sensor varied depending on the operating temperature and the gas spec...

We attempt to meet the general design requirements for high-performance supercapacitor electrodes by combining the strategies of lightweight substrate, porous nanostructure design, and conductivity modification. We fabricate a new type of 3D porous and thin graphite foams (GF) and use as the light and conductive substrates for the growth of metal oxide core/shell nanowire arrays to form integra...

Cobalt oxide (Co3O4) was homogeneously coated on multiwalled carbon nanotube through a simple chemical deposition method and employed in supercapacitor electrodes. SEM image indicated the uniform distribution of Co3O4 nanoparticles on the surface of the multiwalled carbon nanotube. A maximum specific capacitance of 273 Fg(-1) was obtained at the charge-discharge current density of 0.5 Ag(-1). A...

To realize the various functionalities and maximize the structural advantages, hollow particles with multiple compositions and complex structures are highly desirable. However, the development of a convenient and scalable method for the synthesis of such multi-compositionally complex hollow structures remains a big challenge. Herein, we report an efficient and universal strategy to fabricate a ...

Three-dimensional (3D) graphene-based composite materials have attracted increasing attention, owing to their specific surface area, high conductivity and electronic interactions. Here, we report a convenient route to fabricate a 3D Co3O4/Graphene Hydrogel (CGH) composite as an electrode material for supercapacitors. Utilizing the gelation of a graphene oxide dispersion enables the anchoring of...

Transition metal oxides have been suggested as innovative, high-energy electrode materials for lithium-ion batteries because their electrochemical conversion reactions can transfer two to six electrons. However, nano-sized transition metal oxides, especially Co3O4, exhibit drastic capacity decay during discharge/charge cycling, which hinders their practical use in lithium-ion batteries. Herein,...

The functionality or oxidation state of cobalt within a silica matrix can be tailored through the use of cationic surfactants and their halide counter ions during the sol-gel synthesis. Simply by adding surfactant we could significantly increase the amount of cobalt existing as Co3O4 within the silica from 44% to 77%, without varying the cobalt precursor concentration. However, once the surfact...