Yolk-shelled ZnCo2O4 microspheres: Surface properties and gas sensing application

Abstract

The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 m yolk-shelled ZnCo 2 O 4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo 2 O 4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH 3 and NO 2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo 2 O 4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo 2 O 4 microspheres can be further used in other environment monitoring devices.

Thickness effect on sensing properties of pure Cu2O thin films under sub-ppm O3 levels

“…This result was compared to some recent materials based sensors as tabulated in table 3 [24][25][26][27][28][29][30][31][32][33].…”

Gas Sensing Properties of Cobalt Titanate with Multiscale Pore Structure: Experiment and Simulation

“…Considerable effort has been directed towards optimizing the structural and textural properties of semiconducting metal oxides [4][5][6][7][8][9][10][11]. Among the developed innovative structures, hierarchical structures with morphology and high porosity endow the sensing materials with greater response owing to their high surface area and fast gas transport [12][13][14]. For example, Guo et al elucidated that hierarchical porous hollow TiO 2 nanofibers exhibited a remarkable higher sensing performance due to the peculiar properties arising from a large surface/volume ratio [15].…”

Failure Mechanism of Two-Phase Syntactic Foam Polymer Composites under Different Coating Conditions

“…Cases of fabrication of microspheres from commercially available ceramics microspheres, glass microsphere, or polymers microsphere have been reported in literatures [2,[4][5][6]. Depending on the technique, solid or hollow microspheres are widely used in density and, therefore, are used for different or specific intended applications [7][8][9]. Hollow microspheres (HMs) offers superior properties and diverse range of application in engineering technology.…”

“…Studies on incorporation of microspheres into matrices to produce lightweight material (foams) have been reported in literatures [7,[11][12][13]. Composite materials produced by embedding porous particles in a matrix medium can be referred to SFs.…”