Exposure Surface Active Sites of Perovskite‐Type LaFeO₃ Gas Sensors by Selectively Dissolving La Cations for Enhancing Gas Sensing Properties to Acetone

Abstract

While perovskite metal oxide semiconductors (MOS) gas sensors have great potential for detecting various hazardous gases, the surface enrichment of inactive A‐sites severely limits their ability to obtain excellent gas sensing properties. Herein, one simple and facile citric acid etching method is reported with the aim of significantly improving the acetone sensing properties of perovskite LaFeO3 (LFO) by surface structure optimization. Structural characterization shows that citric acid selectively solubilized the A‐site cations and inhibits the occurrence of La segregation on the surface without destroying the perovskite structure, thus increasing the exposure of the active site Fe. At the operating temperature of 200 °C, the response of etched LFO for 20 ppm acetone reaches 50, which is almost 12 times higher than that of pristine LFO sample. Meanwhile, the etched LFO samples also exhibit low detection limits (50 ppb), good selectivity, and stability. The enhanced gas sensitivity is attributed to near‐perfect surface metal ion ratio (La/Fe atomic ratio = 0.97) and abundant oxygen species concentration. This work provides an avenue to enhance the acetone sensing properties and beyond by intentional structural modification, which not only has great scientific meaning, but also valuable potential for industrial and domestic applications.

Smart Humidity Sensor Based on Cs3Cu2I5 Nanorods for Real-Time Monitoring of Leakage of Respiratory Protective Equipment

“…Considering that the relative humidity in human exhaled air is generally close to 100% relative humidity (RH), the humidity sensors based on metal oxide that currently are commonly used are difficult to effectively use in such a high-humidity environment . However, a metal halide perovskite, an excellent gas-sensitive material emerging in recent years, − can still work in a high-humidity environment, in which the lead-free perovskite is ideal for using in RPE due to its environmental friendliness . Ye et al synthesized a humidity sensor based on lead-free perovskite Cs 2 PdBr 6 and used it to check whether fruit is waxed, showing an excellent response/recovery time with 0.4/6.0 s .…”

Fe2O3 Nanorod/Bacterial Cellulose Carbon Nanofiber Composites for Enhanced Acetone Sensing

“…1 It is well-known that the exhaled acetone (C 3 H 6 O) has become one of the most important markers in diabetic diagnosis. 2 Traditional methods in diabetic diagnosis (liquid chromatography tandem mass spectrometry, gas chromatography−mass spectrometry, ion mobility spectrometry, and so on) are limited by their complex equipment, difficult operation, and high cost. 3,4 Owing to the small size, low cost, portability, and simple devices, gas sensors become more and more popular in noninvasive diabetic diagnosis.…”

“…Having a very high mortality and disability rate, diabetes is one of the most common clinical chronic diseases, which has been a worldwide public health problem threatening human health for several years . It is well-known that the exhaled acetone (C 3 H 6 O) has become one of the most important markers in diabetic diagnosis . Traditional methods in diabetic diagnosis (liquid chromatography tandem mass spectrometry, gas chromatography–mass spectrometry, ion mobility spectrometry, and so on) are limited by their complex equipment, difficult operation, and high cost. , Owing to the small size, low cost, portability, and simple devices, gas sensors become more and more popular in noninvasive diabetic diagnosis. , Abundant surface oxygen vacancies in phosphorus-doped porous perovskite nanosheets successfully realized ppb-level C 3 H 6 O detection at 180 °C .…”

Highly Selective and ppb-Level Butanone Sensors Based on SnO2/NiO Heterojunction-Modified ZnO Nanosheets with Electron Polarity Transport Properties

“…Zhu et al 22 changed the basic sites on the ZnO surface via S-doping and thus improved the response to the acidic gas acetic anhydride. Qin et al 23 used acid−base erosion to expose the acid−base sites on the surface of chalcocite to control the highest occupied molecular orbitals and thus achieved improved response of acetone. Selective catalysis to achieve specific bonds also contributes to the selectivity improvement by constructing heterojunctions using noble metals.…”

“…20 Selectivity is an important indicator of gas sensors. There are many strategies to increase the selectivity of gas sensors, including chemical modification methods 21,23 and intelligent identification technologies. 10 However, few studies have increased the selectivity of gas sensing from heterojunction electron transport properties.…”