Recent advances in cataluminescence-based optical sensing systems

Recent advances in the development of cataluminescence focused on oxygen, temperature, catalyst and instrumentation are summarized.

Room-temperature cataluminescence from CO oxidation in a non-thermal plasma-assisted catalysis system

Cataluminescence (CTL) is a kind of chemiluminescence during catalytic reaction on surface of catalysts under a heated condition. Due to the low catalytic reactivity of CO, normally low intensity of CTL is obtained during heterogeneously catalytic oxidation of CO under heated conditions (normally higher than 150°C), even catalyzed by precious-metal-based catalysts. Therefore, seeking enhanced CTL of CO at room temperature and using low-cost catalysts becomes significant. Here, CTL generated from CO oxidation was firstly reported at room temperature, which was carried out in a non-thermal plasma-assisted (NTPA) catalysis system. With air acting as discharge gas, carrier gas as well as oxidant, a Mn/SiO2 nanomaterials-based NTPA catalysis system was fabricated for CO catalytic oxidation at room temperature, whose temperature was much lower than previous CTL methods. Relatively high and selective CTL responses were acquired during CO oxidation on surface of Mn/SiO2 nanomaterials, whereas no significant CTL signal was recorded without plasma assistance or on other metals-doped SiO2 catalysts. Without any excitation light source or heating element, a low cost and simple CO sensor was fabricated by using common and easily synthesized catalysts. The present work has greatly simplified the constructions, and enlarged CTL applications.

High specific surface area LaMO3 (M = Co, Mn) hollow spheres: synthesis, characterization and catalytic properties in methane combustion

LaMO₃ (M = Mn, Co) hollow spheres were synthesized by a carbon sphere template method, while a slow heating rate resulted in multishelled hollow spheres.

Harmful gas recognition exploiting a CTL sensor array

In this paper, a novel cataluminescence (CTL)-based sensor array consisting of nine types of catalytic materials is developed for the recognition of several harmful gases, namely carbon monoxide, acetone, chloroform and toluene. First, the experimental setup is constructed by using sensing nanomaterials, a heating plate, a pneumatic pump, a gas flow meter, a digital temperature device, a camera and a BPCL Ultra Weak Chemiluminescence Analyzer. Then, unique CTL patterns for the four types of harmful gas are obtained from the sensor array. The harmful gases are successful recognized by the PCA method. The optimal conditions are also investigated. Finally, experimental results show high sensitivity, long-term stability and good linearity of the sensor array, which combined with simplicity, make our system a promising application in this field.

STRUCTURAL CHARACTERISTICS OF La2O3 THIN FILM GROWN ON LaB6

Within the framework of hexagonal lanthanum oxide ( h - La 2 O 3) formation, lanthanum hexaboride film on sapphire substrate ( LaB 6/ Al 2 O 3) was oxidized at different temperatures (700-1000 °C) under reduced atmospheric pressure (1·10-2,1.5·10-1Torr) during 30 min. The composition evolution of La 2 O 3/ LaB 6 structure versus annealing temperature has been studied using XRD, FIR reflectivity spectroscopy, SEM and electron probe X-ray microanalysis (EDS). The annealing of the LaB 6 film at T =700 °C under air pressure of 1·10-2 Torr generates thin La 2 O 3 layer which exhibits as inferred from XRD the hexagonal phase. The hydratation of La 2 O 3/ LaB 6/ Al 2 O 3 in distilled water for 30 min and postannealing at 900 °C under air pressure of 1.5·10-1 Torr transform h - La 2 O 3 into hexagonal La ( OH )3 phase accompanied monoclinic LaO ( OH ) and lanthanum oxide carbonate hydrate species.