In-Depth Understanding of the Relation between CuAlO₂ Particle Size and Morphology for Ozone Gas Sensor Detection at a Nanoscale Level

Abstract

A morphology-dependent nanomaterial for energy and environment applications is one of the key challenges for materials science and technology. In this study, we investigate the effect of the particle size of CuAlO 2 nanostructures prepared through the facile and hydrothermal process to detect ozone gas. Phase analysis and structural information were obtained using X-ray diffraction and microRaman studies. The chemical states of CuAlO 2 atomic species were determined by X-ray photoelectron spectroscopy. Electron microscopy images revealed the flower and hexagonal shape constituted of pentagon and oval CuAlO 2 nanoparticles with average size ∼40 and 80 nm. The specific surface area was measured and found to be 59.8 and 70.8 m 2 g −1 , respectively. The developed CuAlO 2 nanostructures not only possess unique morphology but also influence the ozone gas sensing performance. Among the two structures, CuAlO 2 , with hexagonal morphology, exhibited superior ozone detection for 200 ppb at 250°C, with a response and good recovery time of 25 and 39 s compared to the flower morphology (28 and 69 s). These results show that not only does the morphology play an major role but also the particle size, surface area, gas adsorption/desorption, and grain−grain contact, as proposed in the gas sensing mechanism. Finally, we consider CuAlO 2 material as a good candidate for environment monitoring applications.

Highly sensitive and room temperature detection of ultra-low concentrations of O3 using self-powered sensing elements of Cu2O nanocubes

“…4). It is clearly evident that the current across the Cu 2 O nanocube channel increases in the presence of ozone, an observation consistent with the p-type conductivity in Cu 2 O nanocubes since an oxidizing gas such as ozone was expected to remove electrons from the top of the valence band of the semiconductor leading to an increased concentration of holes 21 a process that is discussed in details below. Once the ozone ow is turned off and ambient air is re-injected into the test chamber, the current of the Cu 2 O nanocube channel reduces to almost its original value of z0.525 mA (see the current level following exposure to 10 ppb ozone).…”

Synthesis of CuAlO2 from chemically precipitated nano-sized precursors

“…Hydrothermal synthesis allowed production of CuAlO 2 particles generally around 400 °C [30,31]. Recently, CuAlO 2 nanostructures down to 40 nm were produced at 200 ºC within 12 hours via surfactant-assisted hydrothermal synthesis for ozone sensing applications [25]. Although the synthesis temperature was quite low in this study, nanoparticles were annelaed at 1100 ºC for 5 h to obtain improved crystallinity prior to testing.…”

“…CuAlO 2 also showed promising thermo-electric [20][21][22][23][24], ozone sensing [13,25] photocatalytic hydrogen evolution [26,27] properties and enhanced cathodic photocurrents in p-type dye-sensitized solar cell applications [28,29]. The synthesis of both nanostructured bulk or nanometer size CuAlO 2 powders is critical for many applications, such as thermoelectrics for waste heat recovery or for photoelectrochemical applications, where a high amount of interface is essential.…”

One-step approach for preparing ozone gas sensors based on hierarchical NiCo2O4 structures

“…The patterning of Pt substrates with photolithographic and li-off processes reported in our previous reports. 19,36,37 The substrates were then heated to 80 C for 10 min to evaporate the solvent, followed by calcinations at 350 C for 2 h in an electric furnace in air to stabilize the sample before the gas sensing measurements were performed. The electrical contact and sensor lm illustration mentioned in Fig.…”