Highly Selective Detection of Benzene and Discrimination of Volatile Aromatic Compounds Using Oxide Chemiresistors with Tunable Rh‐TiO₂ Catalytic Overlayers

Abstract

Volatile aromatic compounds are major air pollutants, and their health impacts should be assessed accurately based on the concentration and composition of gas mixtures. Herein, novel bilayer sensors consisting of a SnO2 sensing layer and three different xRh‐TiO2 catalytic overlayers (x = 0.5, 1, and 2 wt%) are designed for the new functionalities such as the selective detection, discrimination, and analysis of benzene, toluene, and p‐xylene. The 2Rh‐TiO2/SnO2 bilayer sensor shows a high selectivity and response toward ppm‐ and sub‐ppm‐levels of benzene over a wide range of sensing temperatures (325–425 °C). An array of 0.5Rh‐, 1Rh‐, and 2Rh‐TiO2/SnO2 sensors exhibits discrimination and composition analyses of aromatic compounds. The conversion of gases into more active species at moderate catalytic activation and the complete oxidation of gases into non‐reactive forms by excessive catalytic promotion are proposed as the reasons behind the enhancement and suppression of analyte gases, respectively. Analysis using proton transfer reaction‐quadrupole mass spectrometer (PTR‐QMS) is performed to verify the above proposals. Although the sensing characteristics exhibit mild moisture interference, bilayer sensors with systematic and tailored control of gas selectivity and response provide new pathways for monitoring aromatic air pollutants and evaluating their health impacts.

Noble Metal Nanoparticles Decorated Metal Oxide Semiconducting Nanowire Arrays Interwoven into 3D Mesoporous Superstructures for Low-Temperature Gas Sensing

“…Surface modification of metal oxides with noble metal nanoparticles (Au, Pt, Pd, etc.) is an effective method to enhance sensitivity and decrease the working temperature of the gas sensor, so as to reduce the power consumption via chemical and electronical sensitization. − Based on the above consideration, design and fabrication of noble nanoparticle-decorated mesoporous materials constructed from metal oxide nanowires is a promising approach to develop high-performance gas sensors which are extremely desired for various miniaturized electric devices.…”

Room-Temperature Catalyst Enables Selective Acetone Sensing

“…Chemical gas sensors are promising for the next generation of handheld devices for air [1] or food quality monitoring [2], medical breath analysis [3] and human detection (e.g., in search and rescue [4] or translational crime control [5]). Additional filters [6] can drastically improve their performance to meet the challenging selectivity requirements of these applications, such as the quantification of single analytes among >800 [7] compounds in breath or >250 [8] in indoor air.…”

“…Particularly interesting are catalytic filters that can convert interferants completely and continuously to sensor-inert species, while target analytes remain unaffected. Such filters have been investigated to remove confounders like CO [9] and ethanol [10] in alkane detection and very recently enabled selective benzene detection [1].…”

Visible-Light-Activated Type II Heterojunction in Cu3(hexahydroxytriphenylene)2/Fe2O3 Hybrids for Reversible NO2 Sensing: Critical Role of π–π* Transition

“…Chemiresistors, including metal oxides, transition metal dichalcogenides, and carbon-based materials, provide a simple and cost-effective method for hazardous gas detection, environmental monitoring, and exhaled breath analysis. − Metal–organic frameworks (MOFs) with ultrahigh porosity, large surface area, and facile chemical tunability − have been considered as viable alternatives for the design of high-performance chemiresistors owing to the recent development of electrically conductive MOFs . Furthermore, not only the metal ions/clusters but also the organic linkers of MOFs can interact with analyte gases, and controllable pore sizes can be used to tune the transport/sieving of gas molecules, enabling the tailored control of gas-sensing characteristics. − …”