In Operando Impedance Spectroscopic Analysis on NiO–WO3 Nanorod Heterojunction Random Networks for Room-Temperature H2S Detection
Autor: | Shun Mao, Haihui Pu, Junhong Chen, Yale Wang, Xiaoyu Sui, Niraj K. Singh, Arnab Maity |
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Jazyk: | angličtina |
Rok vydání: | 2018 |
Předmět: |
Diffraction
Detection limit Fabrication Materials science business.industry General Chemical Engineering Hydrogen sulfide Non-blocking I/O Heterojunction 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences lcsh:Chemistry chemistry.chemical_compound chemistry lcsh:QD1-999 Optoelectronics Nanorod 0210 nano-technology business Electrical impedance |
Zdroj: | ACS Omega, Vol 3, Iss 12, Pp 18685-18693 (2018) |
ISSN: | 2470-1343 |
Popis: | The use of metal-oxide sensors for effectively detecting hydrogen sulfide (H2S) gas at room temperature is currently hindered by their inadequate sensitivity and selectivity. Using a lucid fabrication strategy, we report a room-temperature, highly sensitive, and selective H2S gas sensor using NiO-modified WO3 nanorod (one-dimensional-one-dimensional) random networks. The observed improvements in gas-sensing sensitivity stem from the synergistic effects of various contributions inside the sensing heterostructure, such as bulk nanorod, p-n heterojunction at the interface of these two dissimilar oxides, and gas-induced conducting species due to sulfurization (WS2-x and NiS1-x ). An in situ impedance measurement during gas exposure was used to investigate the influence of these effects. The analysis revealed that these contributing factors can be either cooperating or competing and lead to either increased or decreased sensitivity, respectively. The presence of semimetallic species (NiS, WS2) was further confirmed by in situ X-ray diffraction analysis of the heterostructure nanorod sample with H2S gas exposure. The related sensing mechanism in the heterostructures is presented with a conduction pathway model. The room-temperature-operated nanorod heterostructure sensors showed a lower detection limit of H2S at ∼0.5 ppm, which is significantly lower than its toxicity limiting value ∼10 ppm, per the Environmental Protection Agency. The nanorod heterostructure sensors can be used for real-time, low-cost, room-temperature alarms in an H2S monitoring system. |
Databáze: | OpenAIRE |
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