Detection of Amine Gases by Inverse Opal Photonic Crystals Infiltrated with Precursor HPQ-Ac of Aggregation-Induced Emission Luminogen

Abstract

In this study, to detect amine gases such as ammonia, a kind of biological gas, with high sensitivity, we fabricated a device that combines an inverse opal photonic crystal (IOPC) and 2-(4-oxo-3,4-dihydroquinazolin-2-yl)phenyl acetate (HPQ-Ac), a precursor of the aggregation-induced emission luminogen. IOPC silica structures (200IOPC, 350IOPC, 500IOPC) with SiO₂ were respectively obtained after calcination with 200, 350, and 500 nm polystyrene (PS) nanoparticles used as templates and tetraethyl orthosilicate (TEOS) formed by self-assembly on a slide glass. Furthermore, mesopore-introduced IOPC (50 nm-350IOPC) was prepared by mixing 350 nm and 50 nm PS particles in TEOS solution. Each IOPC was infiltrated with HPQ-Ac, reacted with ammonia, and the rate of change in emission intensity owing to fluorescence was examined. The highest response was obtained for 350IOPC infiltrated with HPQ-Ac among the three IOPCs without mesopores. The 50 nm-350IOPC had higher sensitivity than 350IOPC and was found to be able to detect 50 ppb ammonia gas.