Sensing performances of pure and hybridized carbon nanotubes-ZnO nanowire networks: A detailed study

Abstract

In this work, the influence of carbon nanotube (CNT) hybridization on ultraviolet (UV) and gas sensing properties of individual and networked ZnO nanowires (NWs) is investigated in detail. The CNT concentration was varied to achieve optimal conditions for the hybrid with improved sensing properties. In case of CNT decorated ZnO nanonetworks, the influence of relative humidity (RH) and applied bias voltage on the UV sensing properties was thoroughly studied. By rising the CNT content to about 2.0 wt% (with respect to the entire ZnO network) the UV sensing response is considerably increased from 150 to 7300 (about 50 times). With respect to gas sensing, the ZnO-CNT networks demonstrate an excellent selectivity as well as a high gas response to NH3 vapor. A response of 430 to 50 ppm at room temperature was obtained, with an estimated detection limit of about 0.4 ppm. Based on those results, several devices consisting of individual ZnO NWs covered with CNTs were fabricated using a FIB/SEM system. The highest sensing performance was obtained for the finest NW with diameter (D) of 100 nm, with a response of about 4 to 10 ppm NH3 vapor at room temperature.

ZnO decorated laser-induced graphene produced by direct laser scribing

“…18 Furthermore, an enhancement of the physical properties of ZnO and carbonbased materials when brought together has also been reported, showing interesting advantages, namely in sensing applications. [19][20][21][22][23] For instance, Lupan et al 19 recently described the inuence on ultraviolet (UV) and gas sensing properties of ZnO nanowires aer combining them with CNTs. These authors observed that the addition of CNTs to the porous ZnO networks led to an enhancement of the sensing properties of ZnO, with an efficient detection of different gases, especially in the case of ammonia.…”

“…Usually, both components are produced separately, with the desired dimensions and morphologies, and then mixed together to form the nal material. 15,19,28 Frequently, this approach involves surface modication of one or both constituents to establish covalent, noncovalent or electrostatic interactions between them, 29,30 resulting in elaborated and time consuming processes. Another approach involves the synthesis of ZnO in the presence of the previously prepared carbon material, onto which the oxide semiconductor grows with the chosen morphology.…”

A Carbon Nanotube–Metal Oxide Hybrid Material for Visible-Blind Flexible UV-Sensor

“…Various carbon allotropes such as fullerenes, carbon nanotubes, and graphene have been studied for nanoelectronics, optoelectronics, supercapacitors, and solar cell applications in the past few decades [15,16]. Several groups have studied the carbon nanotube metal oxide semiconductor network for UV sensing and gas sensing applications [17][18][19][20]. However, improvements in the performance of the device due to the incorporation of carbon allotropes is highly affected by its random aggregation [14].…”

ZnAl2O4 decorated Al-doped ZnO tetrapodal 3D networks: microstructure, Raman and detailed temperature dependent photoluminescence analysis

“…Due to their importance in several technological elds, namely photocatalysis, gas and bio-sensing applications, functionalised zinc oxide (ZnO) micro-and nanostructures constitute an important topic in current worldwide research. [1][2][3][4][5][6][7][8][9][10][11][12][13] The disrupted lattice periodicity at ZnO micro-and nanosurfaces is known to cause an increase in the surface state density, which constitutes the main driving paths of sensing-based applications. 3,[14][15][16][17][18][19] Doping effects, thermal treatments under different atmospheres and coverage of as-grown micro-and nano-ZnO surfaces with continuous dielectric media are known to result in strong modications in the electronic energy levels inside the bandgap and band structure of the semiconductor oxide, with a notable inuence on the optical and electrical material response.…”

“…20,[29][30][31][32][33] Additionally, decorating ZnO micro-and nanostructures with other metal oxides is known to result in numerous heterojunctions with enhanced properties, as in the case of gas sensor applications. 3,4,15,21,34,35 Despite the technological relevance of such hybrid materials, the investigation of fundamental optically active defects and their role in the composite's properties is still scarce. In particular, contactless spectroscopic measurements, such as steady state and transient photoluminescence (PL), are powerful tools to investigate the inuence of bulk and surface/interface defects in such complex hybrid structures.…”