Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 403, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jhazmat.2020.123797
Keywords
Electrochemical gas sensor; Ammonia (NH3); Rate-determining kinetics; Stability
Categories
Funding
- National Research Foundation of Korea (NRF) - Korea government (MSIT) [2018R1A5A1025224, 2019R1F1A1064078]
- National Research Foundation of Korea [2019R1F1A1064078] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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An ultrahigh-sensitive mixed-potential ammonia sensor was developed using a new dual-functional NiWO4 electrocatalyst, demonstrating excellent sensitivity, selectivity, and trace-level NH3 detection ability. Operating at 550 degrees C, the sensor showed rapid response/recovery times and long-term stability for exhaust environment monitoring.
The exhaust monitoring for in-situ quantification of gas pollutants has always been a challenge due to the harsh thermo-chemical environments, for which the solid-electrolyte based gas sensors appear as a realistic solution. In this work, an ultrahigh-sensitive mixed-potential ammonia sensor was developed using a new dual-functional NiWO4 electrocatalyst, synthesized through a low-temperature molten-salt synthesis route. The electrode morphology and diffusion lengths were tuned for optimum performance. The sensor operated at 550 degrees C displayed response of-100 mV to 80 ppm NH3, with response/recovery times of 28/68 s and a record-high sensitivity of 90 mV/decade. Besides, it displayed excellent selectivity and trace-level NH3 detection ability upto 400 ppb. While examining the sensing mechanism, the sensor exhibited an NH3 concentration-dependent transformation of rate-determining kinetics from charge-transfer limited Butler-Volmer type to diffusional mass-transport limited reaction kinetics. Moreover, the remarkable long-term stability with negligible response degradation (< 4%) confirms the suitability of the sensor for exhaust environment monitoring.
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