Fabrication of Cubic p-n Heterojunction-Like NiO/In₂O₃ Composite Microparticles and Their Enhanced Gas Sensing Characteristics

Abstract

Oxide semiconductor In2O3 has been extensively used as a gas sensing material for the detection of various toxic gases. However, the pure In2O3 sensor is always suffering from its low sensitivity. In the present study, a dramatic enhancement of sensing characteristic of cubic In2O3 was achieved by deliberately fabricating p-n heterojunction-like NiO/In2O3 composite microparticles as sensor material. The NiO-decorated In2O3 p-n heterojunction-like sensors were prepared through the hydrothermal transformation method. The as-synthesized products were characterized using SEM-EDS, XRD, and FT-IR, and their gas sensing characteristics were investigated by detecting the gas response. The experimental results showed that the response of the NiO/In2O3 sensors to 600 ppm methanal was 85.5 at 260°C, revealing a dramatic enhancement over the pure In2O3 cubes (21.1 at 260°C). Further, a selective detection of methanol with inappreciable cross-response to other gases, like formaldehyde, benzene, methylbenzene, trichloromethane, ethanol, and ammonia, was achieved. The cause for the enhanced gas response was discussed in detailed. In view of the facile method of fabrication of such composite sensors and the superior gas response performance of samples, the cubic p-n heterojunction-like NiO/In2O3 sensors present to be a promising and viable strategy for the detection of indoor air pollution.

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

“…This phenomenon is dictated by the composition of the sample, which change the surface activity and reaction products [7,22,23] by band bending and formation of electron depletion or space charge layer in the conduction band, so the conductivity of the active materials either decreases or increases [76]. The lower operating temperature may not influence the depletion layer of electrons in TiO2, and the CuO/Cu2O layer has a higher resistance, the current flows through the TiO2 layer which is an n-type semiconductor, but at a higher operating temperature the depletion layer of electrons in TiO2 and the accumulation layer of holes in CuO/Cu2O are also influenced, thus leading to the CuO/Cu2O layer predominating in the sensing mechanism leading to the increase of the heterojunction resistance to the application of the target gas [77]. Figure 5b shows the dynamic response towards hydrogen, n-butanol, 2-propanol, ethanol and acetone for the Ag/TiO2/CuO/Cu2O (Cu60) samples at the optimal OPT of 300C.…”

Influence of tin doping on the liquefied petroleum gas and humidity sensing properties of NiO nanoparticles

“…The worldwide researchers have been trying to fabricate gas and humidity sensor having more sensitivity, long-term stability, and small response and recovery times. There are various literatures reporting the NiO-based gas sensors like Cr-doped NiO [14], NiO/In 2 O 3 [15], TiO 2 nanorods decorated with NiO nanoparticles [16], Ce-doped NiO nanoparticles [17], and NiO-based thin films with Pt surface modifications [18] used for the detection of different gases like xylene, methanol, acetone, nitrogen dioxide, and hydrogen, respectively. But a little attention was given to investigate the LPG as well as humidity sensing of NiO structures.…”

Structural Performance Characteristics of Nanomaterials and Its Application in Traditional Architectural Cultural Design and Landscape Planning

“…Its cyclic state will be destroyed, the almost continuous energy levels will be divided into individual energy levels, and the kubo effect will be produced [19,20]. is is the extreme case of the small size effect.…”