Facile Synthesis of Hierarchical CuO Microspheres and their Gas Sensing Properties for NOx at Room Temperature

Abstract

In this research, hierarchical CuO microspheres have been successfully synthesised by a facile reflux method. Scanning electron microscopy results clearly revealed that the hierarchical CuO microspheres were composed of two-dimensional nanosheets. The morphology of the prepared products could be tailored by changing the precursor concentration. The CuO-2 sample shows a higher NO x gas sensing performance with a low detection limit of 0.97 ppm, high gas response of 64.93 %, and short response time of 5.33 s to 97.0 ppm NO x at room temperature. The CuO-2 sensor also presents good selectivity and stability. The significantly improved gas response was concluded to be related to the well aligned microstructures and the improved conductivity of the CuO-2 sample. The unique hierarchical structure allows effective and rapid gas diffusion towards the sensing surfaces. In addition, the sensing mechanism based on the hierarchical CuO microspheres is discussed.

Metal oxide nanomaterial-based sensors for monitoring environmental NO2and its impact on the plant ecosystem: a review

“…This was attributed to the hierarchical structure of the CuO microspheres that allows for effective and rapid gas diffusion towards the sensing surfaces. 98 The sensor based on CuO virus-like microspheres synthesized by the chemical solution method exhibited a high response of 28.4 and response/recovery times of 22/42 s towards 4 ppm NO 2 at RT. 99 CuO nanoplatelets-based NO 2 gas sensors prepared by sonochemical method revealed an ultra-high response to 40 ppm NO 2 operated at RT.…”

“…P-Type nanostructures, such as CuO, 98–100 NiO, 101–103 and Co 3 O 4 , 104 have also been reported as good NO 2 sensing materials. Hierarchical CuO microspheres prepared by using the facile reflux method exhibited high sensitivity of 64.9 and response time of 5.33 s to 97 ppm at RT.…”

“…Thus, efficient adsorption and desorption of NO 2 gas molecules are feasible that results in high sensitivity of the sensor. P-type nanostructures such as CuO[98][99][100], NiO[101][102][103], and Co 3 O 4[104] have also been reported as good NO 2 sensing materials. Hierarchical CuO microspheres prepared by using the facile reflux method exhibited high sensitivity of 64.9 and response time of 5.33 s to 97 ppm at RT.…”

“…Good selectivity, stability, and low LOD of 0.97 ppm NO x gas are the other advantages of these sensors. This was attributed to the hierarchical structure of CuO microspheres that allows effective and rapid gas diffusion towards the sensing surfaces[98]. The sensor-based on CuO virus-like microspheres synthesized by the chemical solution method exhibited a high response of 28.4 and response/recovery times of 22/42s towards 4 ppm NO 2 at RT[99].…”

Microstructure and Optical Properties of Nanostructural Thin Films Fabricated through Oxidation of Au–Sn Intermetallic Compounds

“…Semiconducting metal oxide nanostructures (SMONs) with a large specific surface area have many active sites that allow them to work as effective catalysts [1,2], active materials in gas-sensing devices [3,4], electrode materials for lithium ion batteries [5], or dye-sensitized solar cells [6]. SMONs based on the transition metal oxides, such as CuO, SnO 2 , ZnO, TiO 2 , Fe 2 O 3 , In 2 O 3 , Co 3 O 4 , and WO 3 , in the form of nanorods, nanoparticles, nanowires, nanospheres, nanosheets, nanotubes, and mesoporous nanostructures [3,[7][8][9] are used especially in gas-sensing applications. One method that has been adopted to improve their sensing performance is the incorporation of metal ions [10,11] (such as noble-metal atoms [12,13]) into the oxide structure or the fabrication of multi-phase SMONs [14,15].…”