Significant Enhancement of Hydrogen-Sensing Properties of ZnO Nanofibers through NiO Loading

Abstract

Metal oxide p-n heterojunction nanofibers (NFs) are among the most promising approaches to enhancing the efficiency of gas sensors. In this paper, we report the preparation of a series of p-NiO-loaded n-ZnO NFs, namely (1−x)ZnO-xNiO (x = 0.03, 0.05, 0.7, 0.1, and 0.15 wt%), for hydrogen gas sensing experiments. Samples were prepared through the electrospinning technique followed by a calcination process. The sensing experiments showed that the sample with 0.05 wt% NiO loading resulted in the highest sensing performance at an optimal sensing temperature of 200 °C. The sensing mechanism is discussed in detail and contributions of the p-n heterojunctions, metallization of ZnO and catalytic effect of NiO on the sensing enhancements of an optimized gas sensor are analyzed. This study demonstrates the possibility of fabricating high-performance H2 sensors through the optimization of p-type metal oxide loading on the surfaces of n-type metal oxides.

Improvement of Ethanol Gas-Sensing Responses of ZnO–WO3 Composite Nanorods through Annealing Induced Local Phase Transformation

“…For example, hydrothermally derived flower-like CeO 2 –SnO 2 composites exhibit improved trimethylamine gas-sensing response than that of the pristine SnO 2 [1]. Moreover, hydrogen-sensing properties of ZnO nanofibers are significantly enhanced through NiO loading in a composite structure [2]. SnO 2 /ZnO hetero-nanofibers demonstrate improved acetone gas-sensing responses in comparison with that of the pristine ZnO nanofibers [3].…”

“…However, developing high gas-sensing responses of the ZnO nanostructures toward various target gases is still highly desired and is technically challenging. Various ZnO-based composite systems incorporated with another binary oxide have been proposed to improve the ZnO gas-sensing properties based on the aforementioned demand [2,4,7]. By contrast, WO 3 is another promising gas-sensing binary oxide.…”

Facile Synthesis of the Composites of Polyaniline and TiO2 Nanoparticles Using Self-Assembly Method and Their Application in Gas Sensing

“…[7]. Generally speaking, they have the advantages of small size, light weight, easy integration and low cost, and are widely used in industrial hazardous gas leakage detection, toxic or harmful gas detection, flammable and explosive gas early warning and other fields [8,9]. However, for their applications in flammable or explosive gas detection, semiconductor gas sensors still have some shortcomings such as long response time, low sensitivity and especially high working temperature.…”

Enhanced Hydrogen Detection in ppb-Level by Electrospun SnO2-Loaded ZnO Nanofibers

“…Gas concentrations were controlled exactly, by varying the ratios of the desired gases to dry air using mass flow controllers. After recording the resistance in air (R a ) and the resistance in the presence of the target gas (R g ) by means of a Keithly source meter, the sensor response (R) was calculated as R = R a /R g (for H 2 and CO gases) and R = R g /R a (for NO 2 gas) [31,32,33,34,35,36,37,38,39]. The response time and the recovery time were defined as the time needed for the resistance to reach 90% of its final value upon exposure to target gas and air, respectively [40].…”