Nanocomposite-Decorated Filter Paper as a Twistable and Water-Tolerant Sensor for Selective Detection of 5 ppb–60 v/v% Ammonia

Abstract

Ammonia (NH 3 ) sensors proposed for the simultaneous exhalation diagnosis, environmental pollution monitoring, and industrial leakage alarm require high flexibility, selectivity, stability, humidity tolerance, and wide-concentration-range detection; however, technical challenges still remain. Herein, twistable and water-tolerant paper-based sensors integrated over surgical masks have been developed for NH 3 detection at room temperature, via decorating specially designed ternary nanocomposites (ternary-NCs) on the commercial filter paper. The NCs consist of a multiwalled carbon nanotube framework with a polypyrrole nanolayer and are further loaded with Pt nanodots. Benefiting from the synergy effect of ternary components, the ternary-NCs exhibit an ultrasensitive response to 5 ppb−60 v/v% NH 3 and present high selectivity confirmed by the theory calculations. Remarkably, the filter-paper-based sensors possess outstanding stability against twisting 0−1080°, along with excellent cuttability and foldability. Critically, such paper-based sensors can be integrated over surgical masks for simulated exhaled diagnosis and display superior water tolerance even being immersed in water for 24 h. Practically, the detecting accuracy of the filter-paper-based sensor toward the simulated exhaled NH 3 , environmental NH 3 pollution, and industrial NH 3 leakage is validated using ion chromatography.

Synthesis of Mesoporous Ag2O/SnO2 Nanospheres for Selective Sensing of Formaldehyde at a Low Working Temperature

“…A high level of formaldehyde gas will arise respiratory illness, eye irritation, risk of immune system damage, and even cancer induction. − The WHO further announced that 2.8 million deaths are linked to indoor air pollution . Therefore, it’s desirable to develop a formaldehyde sensor to monitor and detect indoor pollutants. − Semiconductor metal oxide (SMO)-based gas sensors have been attracting considerable attention due to their low cost, high sensitivity, portability, and easy integration. − They are one of the ideal gas sensors that could be easily applied to track the indoor air quality in residences. The main shortcomings of SMO gas sensors include high working temperatures (150–400 °C) and low selectivity.…”

Flexible Gas Sensors Based on Carbon Nanotube Hybrid Films: A Review

“…Reproduced with permission. [ 45 ] Copyright 2022, The Royal Society of Chemistry. f) Optical image of the transparent and flexible SWCNT network film before and after electrical contact deposition, and the change of conductance with the number of bending up to 200 times in bending test.…”

“…The electron‐rich NH 3 molecules transfer electrons from the nitrogen doublet to the positively charged PPy‐nanolayer backbone, thus triggering a resistance‐increasing response. [ 45 ] As for PANI, this performance improvement could be attributed to the synergistic effect and the deprotonation/protonation process between CNTs and PANI. CNTs can form an interconnected network structure with PANI.…”

“…Polymers and NH 3 , reproduced with permission. [ 45 ] Copyright 2022, American Chemical Society. Bending, reproduced with permission.…”

Electrochemical sensing mechanism of ammonium ions over an Ag/TiO2 composite electrode modified by hematite

“…A self-supported hierarchical structure can effectively improve the electrochemical sensing performance of sensors due to the increased active sites, enhanced stability and mass transfer ability, and good contact between the active materials and the substrate. 8,13 TiO 2 nanotube arrays (TNTs) are widely used as self-supporting supports in electrocatalysts and sensors because of their fine chemical stability, large specific surface area, and highly oriented charge transfer channels. 14 Herein, for the first time we demonstrate a new electrochemical sensing mechanism of NH 4 + over a self-supporting Ag/Fe 2 O 3 /TNT sensor.…”