Regulating the Sensitivity and Operating Temperatures by Morphology Engineering of 2D ZnO Nanostructures and 3D ZnO Microstructures for the Detection of Organic-Amines

Abstract

Two-dimensional (2D) materials possess unique properties and advantages in catalysis, photo/-electronic and sensor devices. Here, we proposed a facile route to synthesize 2D ZnO nanoplates with grids by the oxalic-acid-assisted hydrothermal method. Morphology evolutions of ZnO from 3D flower-like microparticles to 2D nanonets were achieved by changing the heat-treatment temperature. By substitution for oxalic acid, 3D ZnO cagelike spheres and hexagonal prism were obtained. The results show that 2D and 3D morphologies of ZnO can be controlled easily by changing calcinations temperatures and additives. The as-prepared ZnO was used as sensing materials for the detection of volatile organic compounds, which indicate that their responses and selectivity are strongly dependent on the diversity of ZnO morphologies. Particularly, 2D ZnO nanonets-based sensor has been proved to detect triethylamine (TEA) efficiently, and it exhibits maximum sensitivity (213.3) on the exposure of 100 ppm triethylamine at 260 °C. Its transient response time is 1 s and recovery time is only 5 s exposed 300 ppm TEA, and the low detection limit is 63 ppb, implying 2D ZnO nanonets can be served as an efficient sensor platform for the detection of TEA.

Heterogeneous Co3O4/Carbon Nanofibers for Low Temperature Triethylamine Detection: Mechanistic Insights by Operando DRIFTS and DFT

“…The rapid progress of materials research has enabled significant advancement of gas sensor technology. [ 7–9 ] Currently, metal oxide semiconductors (MOS) are widely used in gas sensors for VOC detection, [ 10,11 ] especially SnO 2 , [ 12,13 ] ZnO, [ 14,15 ] WO x , [ 16–18 ] and Co 3 O 4 [ 19,20 ] have been extensively studied as TEA sensors. However, the high operating temperature and poor selectivity of MOS remarkably limits its practical applications.…”

“…[ 8,21 ] Substantial efforts have been made by researchers to address these obstacles. Generally these strategies include the design of specific nanostructures, [ 14,22 ] fabrication of heterostructures, [ 23–25 ] surface modification of MOS by catalysts, [ 26 ] and creation of atomic defects such as oxygen vacancy. [ 15,27 ] These approaches have been widely used to change or improve the electronic and chemical properties at the materials’ surface or interface, [ 14,28 ] and have led to a substantial amount of reports of improved TEA sensors.…”

Progress on two-dimensional binary oxide materials

“…However, most bulk transition metal oxides have strong interlayer ionic bonds and no obvious layered structure, which makes it difficult to obtain their 2D nanosheets by exfoliation. Non-vdW oxides that are commonly used include In 2 O 3 , 63 TiO 2 , [64][65][66][67][68][69][70][71][72][73] CeO 2 , 74 Gd 2 O 3 , 75 NiO, [76][77][78][79] [87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105] ZnO, [106][107][108][109][110][111][112][113][114] WO 3 , [48][49][50] and so on. Due to the 3D block structure, only the outermost atoms and active sites on the surface can play a role, while other atoms and active sites are covered, which is far from the full utiliza...…”

“…This technology can be used to prepare optically passivated mixed metal oxide films as counter electrodes with high light transmittance and good cycling stability. Dahal et al 138 demonstrated the insertion of a grown 2D FeO layer between CVDgrown graphene and a Pt (111) substrate by continuously inserting iron and oxygen, which could separate the graphene from the metal substrate. They showed that metal-stabilized 2D oxidized monolayers can grow between graphene and metal substrates to form 2D heterostructures that can adjust films, grown at an oxygen content of 1/16 and 1/32 and annealed at 500 °C/1 h. The substrates used are ordinary glasses.…”

Two-Dimensional Layered Materials Offering Expanded Applications in Flatland

“…BP has also been used as an efficient artificial substrate for DNA replication . Layered transition-metal oxides have been less explored; one of the reasons could be their wide band gap, which renders them electrically insulating. − However, a new study has shown that n-type conduction can be induced in α-MoO 3 either by H + -ion intercalation, which creates oxygen vacancies, or by fluorine doping . Oxygen vacancies can also play an important role in enhancing the gas-sensing capabilities in devices based on α-MoO 3 .…”