Development of high-performance sensor based on NiO/SnO₂ heterostructures to study sensing properties towards various reducing gases

Abstract

In this work, we report the spontaneous formation of NiO nanoparticles-decorated onto smooth SnO2 nanofibers, which is an inexpensive and scalable method for yielding a high composite surface area via a simple two-step synthesis process based on electrospinning and the hydrothermal method. A Nickel Oxide proton-conducting electrolyte is deposited homogeneously over a large surface area in a transparent solution, mixed and decorated onto Tin dioxide nanofibers, as evidenced by cross sectional imaging of the electrospun nanofibers. The composite based on nanoparticle-decorated fibers enlarges the surface area of the exposed electrolyte, which fundamentally improves the overall gas sensing performance. The crystal structure, morphology, and physio-chemical surface state of the NiO/SnO2-based specimen are comprehensively examined using XRD, SEM, TEM, HRTEM, EDX, and photoelectron (XPS) spectroscopy. The composite based on NiO/SnO2 nanoparticle-decorated fibers exhibits an optimistic mesoporous nature with a huge specific area, which is key for superior gas sensors. The result reveals that NiO/SnO2 nanoparticle-decorated fibers with an average size of 180–260 nm in diameter, where the average length of fibers was about 1.5 μm. The composite-based heterojunction of NiO/SnO2 nanoparticle-decorated fibers enhances the adsorption of oxygen molecules, which show fast response, good selectivity and quick recovery speed against ethanol gas at an optimal temperature of about 160 °C. The maximum sensitivity response of the sensor-based composite NiO/SnO2 nanoparticle-decorated fibers was 23.87 in respect of 100 ppm ethanol gas at a low temperature of 160 °C; this is approximately about 7.2 times superior to that of pure SnO2 nanofibers. The superior gas sensing capabilities of a composite based on NiO/SnO2 nanoparticle-decorated fibers may be attributable to the enhanced catalytic effect of the small sized NiO nanoparticles on smooth SnO2 nanofibers, together with the p/n heterojunction effects between NiO and SnO2 heterostructures.

Top-Down Approaches for 10 nm-Scale Nanochannel: Toward Exceptional H2S Detection

“…The SnO 2 −NiO nanopattern sensor shows a faster response time due to the catalytic effect of NiO enabling a lower activation energy for dissociation of analytes and O 2 . 29,30 To check the detection selectivity, we tested cross-sensitivity of the sensors to a total of 11 different gases compared to H 2 S (Figure 5c). We selected VOCs (toluene, hexane, propanal, acetone, ethanol), reducing gases (NO, NH 3 , H 2 ), and oxidizing gases (SO 2 , CO 2 , NO 2 ) as reference gases for two reasons: First, VOCs are easily found in exhaled breath of human to detect halitosis, and second, reducing and oxidizing gases are easily found in industrial monitoring.…”

“…Real-time sensor data for various H 2 S concentration and response/recovery time are shown in Figures S6 and S7, respectively (performance of SnO 2 –Au is shown in Figure S8). The SnO 2 –NiO nanopattern sensor shows a faster response time due to the catalytic effect of NiO enabling a lower activation energy for dissociation of analytes and O 2 . , …”

“…Furthermore, it is noticeable that the gas response of NO 2 is 21.87-times higher in the SnO 2 –NiO nanopattern ( R NO 2 / R air = 190.59) than in the SnO 2 nanopattern ( R NO 2 / R air = 8.72). In addition, even though all gases including VOCs, reducing gases, and oxidizing gases showed enhanced sensitivity with NiO doping from p–n junction, NO 2 especially showed the largest enhancement, which is attributed to distinct catalytic properties of NiO to NO 2 molecules. − Since the H 2 S and NO 2 signal directions are totally different, the SnO 2 –NiO nanopattern sensor shows good selectivity toward both gases, having potential that can be applied in various fields including breath analysis and hazardous gas detection in industries.…”

Nanoscale Heterostructured Materials Based on Metal Oxides for a Chemiresistive Gas Sensor

“…and/or p-type (CuO, NiO, Co 3 O 4 etc.) metal oxides that show different sensing properties depending on the way they are formed. − Various studies revealed that the existence of such heterojunctions facilitates gas sensing phenomenon by electron/hole movement through the interface modulated potential barrier. When two different metal oxides are in physical contact, the Fermi level of the hybrid material must align.…”

NiO-Based Gas Sensors for Ethanol Detection: Recent Progress

“…In recent years, NiO has been reported to recombine with n-type semiconductors such as ZnO [63,[100][101][102][103][104][105][106][107][108][109][110], SnO 2 [67,[111][112][113][114][115][116][117][118], WO 3 [119][120][121], Fe 2 O 3 [122][123][124], and In 2 O 3 [125,126].…”