Porous Titania Nanosheets as Micro-Gravimetric Sensing Material for Trace NO2 Detection

AbstractNanostructured tungsten oxide synthesized from SiO2 templates (SBA-15 and KIT-6) has been used for NO2 gas sensing. Chromium has been added as catalytic additive to WO3 in order to enhance sensor response. Several techniques have been used for identifying both additive location in the tungsten oxide matrix and its oxidation state. Raman spectroscopy confirmed the presence of terminal chromium-oxygen bonds at the material surface. Besides, X-ray photoelectron spectroscopy showed chromium peaks attributable to Cr(III) species. Electrical behavior of pure WO3 has found to be highly dependent on the nanostructure type, i. e. 2D SBA-15 and 3D KIT-6 replicas. Chromium addition diminishes response time and improves sensor response at low NO2 concentrations. Electrical differences due to WO3 nanostructure disappears as a result of additive introduction in the material.

Download Full-text

Synthesis of Highly Active Sub‐Nanometer Pt@Rh Core–Shell Nanocatalyst via a Photochemical Route: Porous Titania Nanoplates as a Superior Photoactive Support

Small ◽

10.1002/smll.201603879 ◽

2017 ◽

Vol 13 (16) ◽

pp. 1603879 ◽

Cited By ~ 29

Author(s):

Wen‐Wen Zhan ◽

Qi‐Long Zhu ◽

Song Dang ◽

Zheng Liu ◽

Mitsunori Kitta ◽

...

Keyword(s):

Core Shell ◽

Highly Active ◽

Porous Titania ◽

Photochemical Route

Download Full-text

Optimization of a Low-Power Chemoresistive Gas Sensor: Predictive Thermal Modelling and Mechanical Failure Analysis

Sensors ◽

10.3390/s21030783 ◽

2021 ◽

Vol 21 (3) ◽

pp. 783 ◽

Cited By ~ 1

Author(s):

Andrea Gaiardo ◽

David Novel ◽

Elia Scattolo ◽

Michele Crivellari ◽

Antonino Picciotto ◽

...

Keyword(s):

Low Power ◽

Failure Analysis ◽

Gas Sensors ◽

High Performance ◽

Gas Sensing ◽

Mechanical Failure ◽

Sensing Applications ◽

Theoretical Approaches ◽

Sensing Material ◽

Silicon Bulk

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.

Download Full-text

Anatase porous titania nanosheets for resonant-gravimetric detection of ppb-level NO2 at room-temperature

The Analyst ◽

10.1039/d1an00424g ◽

2021 ◽

Author(s):

Jialin Yang ◽

Ding Wang ◽

Ming Li ◽

Haitao Yu ◽

Pengcheng Xu ◽

...

Keyword(s):

Public Health ◽

Environmental Protection ◽

Room Temperature ◽

Trace Level ◽

Porous Titania

The trace-level detection to harmful NO2 gas at room-temperature is very important for environmental protection and public health. This paper reports the resonant-gravimetric detection of ppb-level NO2 at room-temperature using...

Download Full-text

A Molecularly Imprinted Sol-Gel Electrochemical Sensor for Naloxone Determination

Nanomaterials ◽

10.3390/nano11030631 ◽

2021 ◽

Vol 11 (3) ◽

pp. 631

Author(s):

Narges Shaabani ◽

Nora W. C. Chan ◽

Abebaw B. Jemere

Keyword(s):

Indium Tin Oxide ◽

Sol Gel ◽

Electrochemical Techniques ◽

Electrochemical Determination ◽

Multiwall Carbon Nanotube ◽

Molecularly Imprinted ◽

Gel Layer ◽

Sensing Material ◽

Relative Standard ◽

Optimized Conditions

A molecularly imprinted sol-gel is reported for selective and sensitive electrochemical determination of the drug naloxone (NLX). The sensor was developed by combining molecular imprinting and sol-gel techniques and electrochemically grafting the sol solution onto a functionalized multiwall carbon nanotube modified indium-tin oxide (ITO) electrode. The sol-gel layer was obtained from acid catalyzed hydrolysis and condensation of a solution composed of triethoxyphenylsilane (TEPS) and tetraethoxysilane (TES). The fabrication, structure and properties of the sensing material were characterized via scanning electron microscopy, spectroscopy and electrochemical techniques. Parameters affecting the sensor’s performance were evaluated and optimized. A sensor fabricated under the optimized conditions responded linearly between 0.0 µM and 12 µM NLX, with a detection limit of 0.02 µM. The sensor also showed good run-to-run repeatability and batch-to-batch performance reproducibility with relative standard deviations (RSD) of 2.5–7.8% (n = 3) and 9.2% (n = 4), respectively. The developed sensor displayed excellent selectivity towards NLX compared to structurally similar compounds (codeine, fentanyl, naltrexone and noroxymorphone), and was successfully used to measure NLX in synthetic urine samples yielding recoveries greater than 88%.

Download Full-text

Acid is a potential interferent in fluorescent sensing of chemical warfare agent vapors

Communications Chemistry ◽

10.1038/s42004-021-00482-6 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Shengqiang Fan ◽

Genevieve H. Dennison ◽

Nicholas FitzGerald ◽

Paul L. Burn ◽

Ian R. Gentle ◽

...

Keyword(s):

Chemical Warfare Agents ◽

Chemical Warfare Agent ◽

Chemical Warfare ◽

Standard Laboratory ◽

Care Needs ◽

Fluorescent Sensing ◽

Sensing Systems ◽

Sensing Material ◽

Fluorescence Change ◽

Warfare Agents

AbstractA common feature of fluorescent sensing materials for detecting chemical warfare agents (CWAs) and simulants is the presence of nitrogen-based groups designed to nucleophilically displace a phosphorus atom substituent, with the reaction causing a measurable fluorescence change. However, such groups are also basic and so sensitive to acid. In this study we show it is critical to disentangle the response of a candidate sensing material to acid and CWA simulant. We report that pyridyl-containing sensing materials designed to react with a CWA gave a strong and rapid increase in fluorescence when exposed to Sarin, which is known to contain hydrofluoric acid. However, when tested against acid-free diethylchlorophosphate and di-iso-propylfluorophosphate, simulants typically used for evaluating novel G-series CWA sensors, there was no change in the fluorescence. In contrast, simulants that had been stored or tested under a standard laboratory conditions all led to strong changes in fluorescence, due to acid impurities. Thus the results provide strong evidence that care needs to be taken when interpreting the results of fluorescence-based solid-state sensing studies of G-series CWAs and their simulants. There are also implications for the application of these pyridyl-based fluorescence and other nucleophilic/basic sensing systems to real-world CWA detection.

Download Full-text

First-Principles Study of Au-Doped InN Monolayer as Adsorbent and Gas Sensing Material for SF6 Decomposed Species

Nanomaterials ◽

10.3390/nano11071708 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1708

Author(s):

Ruochen Peng ◽

Qu Zhou ◽

Wen Zeng

Keyword(s):

Power Systems ◽

Molecular Orbital ◽

First Principles ◽

Recovery Time ◽

Sulfur Hexafluoride ◽

Gas Sensing ◽

Normal Operation ◽

Frontier Molecular Orbital ◽

Adsorption System ◽

Sensing Material

As an insulating medium, sulfur hexafluoride (SF6) is extensively applied to electrical insulation equipment to ensure its normal operation. However, both partial discharge and overheating may cause SF6 to decompose, and then the insulation strength of electrical equipment will be reduced. The adsorption properties and sensing mechanisms of four SF6 decomposed components (HF, SO2, SOF2 and SO2F2) upon an Au-modified InN (Au-InN) monolayer were studied in this work based on first-principles theory. Meanwhile, the adsorption energy (Ead), charge transfer (QT), deformation charge density (DCD), density of states (DOS), frontier molecular orbital and recovery property were calculated. It can be observed that the structures of the SO2, SOF2 and SO2F2 molecules changed significantly after being adsorbed. Meanwhile, the Ead and QT of these three adsorption systems are relatively large, while that of the HF adsorption system is the opposite. These phenomena indicate that Au-InN monolayer has strong adsorption capacity for SO2, SOF2 and SO2F2, and the adsorption can be identified as chemisorption. In addition, through the analysis of frontier molecular orbital, it is found that the conductivity of Au-InN changed significantly after adsorbing SO2, SOF2 and SO2F2. Combined with the analysis of the recovery properties, since the recovery time of SO2 and SO2F2 removal from Au-InN monolayer is still very long at 418 K, Au-InN is more suitable as a scavenger for these two gases rather than as a gas sensor. Since the recovery time of the SOF2 adsorption system is short at 418 K, and the conductivity of the system before and after adsorption changes significantly, Au-InN is an ideal SOF2 gas-sensing material. These results show that Au-InN has broad application prospects as an SO2, SOF2 and SO2F2 scavenger and as a resistive SOF2 sensor, which is of extraordinary meaning to ensure the safe operation of power systems. Our calculations can offer a theoretical basis for further exploration of gas adsorbent and resistive sensors prepared by Au-InN.

Download Full-text