Abstract
In this work, we investigate the catalytic effects of gold (Au) and platinum (Pt) nanoparticle layer deposition on highly sensitive zinc oxide (ZnO) nanowires (NWs) used for selective H2S detection in the sub-ppm region. Optimum quality pristine ZnO NWs were grown by high temperature chemical vapor deposition (CVD) in the vapor liquid solid growth (VLS) mode on silicon with a thin Au layer acting as a growth catalyst. The surface of pristine ZnO NWs was modified by systematic magnetron sputtering of discontinuous Au and Pt layers of 0–5 nm thickness. Resistive gas sensors based on the gas sensing mechanism of a chemical field effect transistor (ChemFET) with open gate, which is formed by hundreds of parallel aligned pristine Au-modified or Pt-modified ZnO NWs, were measured toward H2S diluted in dry nitrogen (N2) or in dry synthetic air at room temperature. Gas sensing results showed a largely improved response due to the catalytic effects of metal deposition on the ZnO NW surface. Controlled application of ZnO NW growth under optimized conditions and metal catalyst deposition showed a clear response enhancement toward 1 ppm H2S from the initial 20% achieved with pristine ZnO to over 5000% with ZnO NWs covered by 5 nm of Au, and, hence, significantly lower than the limit of detection.
Highlights
Over the past decade, numerous publications highlighted the medical role of hydrogen sulfide (H2S) for therapeutic applications and early diagnostics [1,2], traced in medical breath analysis e.g., with the “electronic nose” approach [3]
Since the SNR for both sensors with pristine zinc oxide (ZnO) NWs appeared was close to 2, and the noise is very high in comparison to the detection signal, an estimation of the response for both sensors was difficult
H2S gas detection in the low ppb concentration range was successfully performed with pristine, Au modified and Pt modified ZnO NWs
Summary
Numerous publications highlighted the medical role of hydrogen sulfide (H2S) for therapeutic applications and early diagnostics [1,2], traced in medical breath analysis e.g., with the “electronic nose” approach [3]. It was shown that abnormal endogenous H2S concentration levels in exhaled breath samples can be linked to airway inflammation in asthma patients, and H2S functions as a potent biomarker. Using ion-molecule reaction-mass spectrometry, Milloning et al successfully linked an exhaled trace amount of 1.9 ppb of H2S to gastroesophageal cancer [4]. Zhang et al studied eosinophilic asthma and paucigranulocytic asthma in 97 patients In their studies, both chronic asthma types showed correlation to exhaled endogenous H2S concentrations of 7.7 ppb and 11.1 ppb, respectively [5]. Breath sample preparation and analysis rely on Proceedings 2020, 4, x; doi: FOR PEER REVIEW www.mdpi.com/journal/proceedings
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
