Highly Sensitive and Selective NiO/WO₃ Composite Nanoparticles in Detecting H₂S Biomarker of Halitosis

Abstract

Indirectly monitoring halitosis via the detection of hydrogen sulfide (H2S) biomarkers using gas sensors is a newly emerging technique. However, such H2S sensors are required with critically high selectivity and sensitivity, as well as a ppb-level detection limit, which remains technologically challenging. To address such issues, here, we have developed highly sensitive and selective H2S sensors with NiO/WO3 nanoparticles (NPs), which have been synthesized by firstly hydrolyzing WO3 NPs and subsequently decorating with NiO NPs in a hydrothermal process. Theoretically, the NiO/WO3 NPs assist in forming a thicker electron depletion layer, adsorbing more oxygen species O2 – to oxidize H2S and finally release more electrons. Beneficially, 2.1 wt % NiO/WO3 NPs show high sensitivity to H2S (R a/R g = 15031 ± 1370 @ 10 ppm, 100 °C), which is 42.6-fold higher than that of the pristine WO3 NPs (R a/R g = 353 ± 5.6 @ 10 ppm, 100 °C). Further, the H2S sensor shows ppb-level detection limit (R a/R g = 4.95 ± 2.9 @ 0.05 ppm, 100 °C) and high selectivity. Practically, NiO/WO3 NP sensor prototype has been employed to detect the simulated exhaled halitosis compared with that of gas chromatography, revealing a close concentration of H2S. Our investigation offers an experimental base in future intelligent medical applications.

Fe‐doped MOF‐derived N‐rich porous carbon nanoframe for H2S cataluminescence sensing

“…It is usually produced from automobile exhaust, waste disposals, the petrochemical industry, natural gas exploitation industry, and coal mining industry, and other places. [ 1–5 ] Long‐term expose to certain amounts of H 2 S gas not only causes a sense of smell loss, but also causes neural paralysis. When the concentration of H 2 S surpasses the critical value of 250 ppm, human death will happen if inhaled accidentally.…”

ZnO@CuO hollow nanosphere-based composites used for the sensitive detection of hydrogen sulfide with long-term stability

“…Currently, several methods, including colorimetric assays, [8][9][10] chromatography, [11][12][13] uorometry, [14][15][16][17] electrochemical analysis, 18,19 and gas-sensing analysis, [20][21][22] have been applied for hydrogen sulde detection. As a typical gas-sensing material, metal oxide semiconductors, including ZnO, 23,24 CuO, 25,26 SnO 2 , 27,28 In 2 O 3 , 29,30 WO 3 , 31,32 Co 3 O 4 , 33,34 NiO, 35,36 Fe 2 O 3 , 37,38 and Cr 2 O 3 , 39 have been widely applied for the detection of various gaseous substances, like H 2 S, due to their thermal endurance, physical stability, and low cost. However, some drawbacks, such as high working temperature and low selectivity, restrict the practical applications of H 2 S gas sensors.…”

Trace Hydrogen Sulfide Sensing Inspired by Polyoxometalate-Mediated Aerobic Oxidation

“…Contemporary technologies for H 2 S detection include gas chromatography, 8 , 9 metal oxide/nanoparticle chemiresistors, 10 − 13 electrochemical sensors, 14 , 15 and colorimetric and chemiluminescence-based probes. 6 , 16 − 22 Although high H 2 S sensitivities have been achieved in some instances, typical drawbacks of contemporary technologies include long response times, elevated operational temperatures, high power requirements, cross-selectivity issues with respect to volatile organic compounds (VOCs), bulky device enclosures, slow or sluggish signal reversibility, and short sensor lifetimes that hamper mobile deployment and real-time H 2 S monitoring.…”

“…Contemporary technologies for H 2 S detection include gas chromatography, , metal oxide/nanoparticle chemiresistors, − electrochemical sensors, , and colorimetric and chemiluminescence-based probes. ,− Although high H 2 S sensitivities have been achieved in some instances, typical drawbacks of contemporary technologies include long response times, elevated operational temperatures, high power requirements, cross-selectivity issues with respect to volatile organic compounds (VOCs), bulky device enclosures, slow or sluggish signal reversibility, and short sensor lifetimes that hamper mobile deployment and real-time H 2 S monitoring. Therefore, it is imperative to develop new H 2 S sensing technologies that satisfy a range of key criteria for in-field application such as fast room temperature operation, low power requirements, rapidly reversible H 2 S response, high selectivity, and consistent device performance over time.…”