Role of cobalt in Co-ZnO nanoflower gas sensors for the detection of low concentration of VOCs

Enhanced detection of low concentration volatile organic compounds using advanced doped zinc oxide sensors

“…Thus, the adsorbed oxygen ionization equations can be written by the following equations:O 2(gas) → O 2(ads) O 2(ads) + 4e − → 2O (ads) 2− .When we inject a reducing gas into the tested cell, the molecules of the gas will react with the oxygenated species on the surface of the material which causes a reinjection of electrons in our detection material and subsequently the potential barrier will be reduced and the conductivity will be increased. The reactions between the VOCs gases (ethanol, formaldehyde, methanol, and acetone) and the oxygen species are expressed by the following equations: 35 C 2 H 5 OH (gas) + O (ads) 2− → CH 3 CHO (ads) + H 2 O + 2e − HCOH (gas) + 2O (ads) 2− → CO 2(gas) + H 2 O + 4e − CH 3 OH (gas) + O (ads) 2− → H 2 CO (gas) + H 2 O + 2e − CH 3 COCH 3(gas) + 8O (ads) 2− → 3CO 2(gas) + 3H 2 O + 16e − .…”

Metal oxide semiconductor gas sensing materials for early lung cancer diagnosis

“…Binary metal oxide semiconductors refer to the oxide phase composed of one kind of metal atom, and it is usually segmented into type n and p based on the charge carriers. Common n-type metal oxides include ZnO, SnO 2 , WO 3 , α-Fe 2 O 3 , and CeO 2 , while p-type metal oxides include Co 3 O 4 , NiO, CuO, and Mn 3 O 4 [30,43,44]. The binary metal oxide is the metal oxide gas sensing material that has been mainly studied.…”

“…Pretreatment processes such as dehumidification and filter are significant to improve the accuracy of breath diagnosis when the resistance property of metal oxide materials cannot meet the requirement. An ideal respiratory gas sensor should have excellent selectivity, moisture Biomarker n-propanol [28] Toluene [29] Isoprene [30,31] Cyclohexane [28] Acetaldehyde [32] Formaldehyde [33,34] resistance, ppb-level detection limit, and high sensitivity. Therefore, it is urgent to develop gas sensing materials with excellent performance to meet the requirements of LC respiratory diagnosis.…”

Review on Porosity Control in Nanostructured Semiconducting Metal Oxides and Its Influence on Chemiresistive Gas Sensing

“…In recent years, there has been a growing interest in the synthesis and application of chemiresistive materials such as semiconducting metal oxides (SMOs), − metals, , transition-metal dichalcogenides, − metal–organic frameworks, graphite, graphene, , black phosphorus, , MXenes, and their composites − for gas-sensing applications. Among them, SMOs have been widely used as gas-sensing layers due to their superior gas sensitivity at elevated temperatures. − In particular, nanostructured materials have been actively investigated in the gas sensor .…”