Restored operation lifetime of Au@ZnO NW gas sensors for H₂S detection due to reversible sulfurization with NO₂ and O₃
Year: 2026
Type: preprint
Abstract: The nanomaterial system of gold functionalized zinc oxide nanowires (Au@ZnO NWs) shows extraordinary sensing ability towards trace amounts of hydrogen sulfide (H 2 S), meeting the requirements for early medical diagnostics via exhaled human breath. An interplay of morphological and chemical sensitization of ZnO NWs with Au nanoparticles (Au NPs) enables the selective detection of H 2 S concentrations at the ppt (parts-per-trillion) concentration level at room temperature. Exceptional sensitivity and selectivity are achieved through dissociative chemisorption of H 2 S on both the Au NP surface, and the ZnO NW [10-10] side-factette. Unfortunately, this interaction leads to the sulfurization of the sensor, deteriorates the gas sensitive surface of the nanomaterial system and significantly shortens the lifetime of Au@ZnO NW gas sensors. In this work, we investigate and successfully demonstrate a complete reversal of the sensor’s deterioration, which is achieved by flushing the affected nanomaterial with potent oxidants, namely NO 2 and ozone (O 3 ). Gas sensing performance is assessed in current-over-time measurement ( I - t ) of Au@ZnO chemically sensitive field effect transistors (ChemFETs). Here, functionalized nanowires form the gas-sensitive open gate. We present the initial deterioration of sensors caused by sulfur poisoning of the nanomaterial system, followed by a recovery treatment with either NO 2 , or O 3 . We systematically compare the morphological and chemical effects of each treatment and evaluate the viability of each method by using SEM micrographs, energy-dispersive X-ray spectroscopy (EDX) data and detailed X-ray photoelectron spectroscopy (XPS) analysis. Results indicate that the NO 2 treatment can lead to a complete decomposition of the gassensitive open gate upon prolonged exposure. In contrast, O 3 found to provide a damage-free treatment that completely restores the sensors' sensing properties after less than 30 min of continuous exposure. ( I - t )-measurements verify a sufficient recovery of the initial sensor sensitivity and signal properties after O 3 treatment, which directly extends the operational lifetime of an Au@ZnO NW gas sensors for H 2 S detection.
Source: ChemRxiv
Institution: Universität Ulm
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214741632