Photoluminescence of Zn5(CO3)2(OH)6 nanoparticles synthesized by utilizing CO2 and ZnO water slurry

Abstract

Zinc carbonate hydroxide, Zn5(CO3)2(OH)6, nanoparticles were conveniently synthesized from zinc oxide (ZnO) fine powders and photoluminescence of the synthesized Zn5(CO3)2(OH)6 powder was investigated. The synthesized fine ZnO powder was mixed in water to prepare a ZnO slurry. The ZnO slurry was then reacted with CO2 at 25 °C to produce Zn5(CO3)2(OH)6. The amount of Zn5(CO3)2(OH)6 increased as the mass ratio of water/ZnO and the time of the reaction of CO2 with the ZnO slurry was increased. The synthesized Zn5(CO3)2(OH)6 powder exhibited a strong blue-purple emission at around 375 nm under UV-light excitation at 286 nm, while the fine ZnO powder exhibit a weak red-purple emission at around 425 nm under UV-light excitation at 258 nm. The intensity of the blue-purple emission was increased with increasing the amount of Zn5(CO3)2(OH)6. The emission spectra of Zn5(CO3)2(OH)6 was different from ZnO and other zinc carbonate hydroxides such as Zn4CO3(OH)6・H2O.The blue-purple emission, owing to Zn–O charge transfer transition of the Zn5(CO3)2(OH)6, was increased with increasing UV absorption intensity of electron transitions in CO32− of Zn5(CO3)2(OH)6. Thus, the Zn5(CO3)2(OH)6 nanoparticle obtained by the conventional and novel synthesis method using ZnO and CO2, exhibit a strong blue-purple emission because of the crystal structure of Zn5(CO3)2(OH)6 having ZnO4 and CO32−.