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...

The spinel Co3O4 has emerged as a promising alternative to noble-metal-based electrocatalysts for electrochemical water electrolysis in alkaline medium. However, pure Co3O4, despite having high activity anodic oxidation, remains inactive toward the hydrogen evolution reaction (HER). Here, Ni-doped (Co3-xNixO4) prepared by simple method exhibits favorable HER and stability (>300 h, whether 1 M K...

Cobalt Oxide/ Zinc Oxide nanocomposite was synthesized by dropwise addition ofCo(NO)3.6H2O and Zn(NO3)2.4H2O solutions to KOH solution at different temperatures followed bycalcination at 300ºC for 4 h. The morphology and structure of nanoparticles and the influence oftemperature on particle size were studied using scanning electron microscopy (SEM) and X-RayDiffraction (XRD). Minimum particle s...

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 ...

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...

Hybrid nanomaterials based on manganese, cobalt, and lanthanum oxides of different morphology phase compositions were prepared using a facile single-step ultrasonic spray pyrolysis (USP) process tested as electrocatalysts for oxygen reduction reaction (ORR). The structural morphological characterizations completed by XRD SEM-EDS. Electrochemical performance was characterized cyclic voltammetry ...