Novel application of Tb-substituted layered double hydroxides to capturing and photoluminescence detecting CO2 gas at ambient temperature

Abstract Terbium-substituted layered double hydroxides with NO3− in the interlayer (NO3-LDH) were synthesized using a hydrothermal method. The synthesized NO3-LDH reacted with CO2 at 30 °C under a CO2 gas flow containing water vapor to produce CO2-absorbed LDH (CO3-LDH). Fluorescent spectroscopy clarified that the intensity of the excitation and emission spectra of the CO3-LDH increased with increasing CO2 absorption time and CO2 concentration under the CO2 gas flow. The CO3-LDH exhibited green photoluminescence owing to the transition of 5D4 → 7FJ (J = 3, 4, 5, 6), which was excited by UV-light irradiation at 353 nm. The bandgap of the CO3-LDH was greater than that of the NO3-LDH, which caused an increase of the intensity of the excitation and emission spectra of the CO3-LDH. It was clarified that the NO3-LDH is capable of capturing CO2 as a carbonate species under water vapor, and resultant CO3-LDH emitted green photoluminescence.