title: Bilayer stabilized Ln³⁺-doped CaMoO₄ nanocrystals with high luminescence quantum efficiency and photocatalytic properties.
abstract: In this article, we discuss the microwave synthesis of sodium dodecyl sulphate (SDS) stabilized Ln(3+)-doped CaMoO4 nanocrystals (Ln(3+) = Eu(3+), Er(3+)/Yb(3+)). The nanocrystals are quite monodispersed with an average size close to 100 nm. FTIR and TGA analyses suggest strong binding of the SDS molecules to the CaMoO4 nanocrystals surface. The high dispersibility of the nanocrystals in water implies that SDS stabilizes the nanocrystals as a bilayer structure. The SDS coating also assists in the easy dispersion of the nanocrystals in toluene without any additional surface chemistry. The Eu(3+) ions doped in the CaMoO4 nanocrystals display very strong red luminescence with a quantum yield close to 40%. Under 980 nm excitation, Er(3+)/Yb(3+)-doped CaMoO4 nanocrystals display Er(3+) emissions at 550 and 650 nm. In addition, interestingly, a NIR peak at around 833 nm is observed, which occurred via a three photon process. Furthermore, the CaMoO4 nanocrystals exhibit photocatalytic activity which is studied through the degradation of Rhodamine B (RhB) dye in neutral conditions. The RhB dye is significantly degraded by ~80% under UV illumination within 4 h and the rate of degradation is comparable to that observed for well known ZnO nanoparticles. The high luminescence quantum efficiency and strong photocatalytic activity of the Ln(3+)-doped CaMoO4 nanocrystals make them a potential material for dual applications such as bio-imaging and photocatalysis.
authors.affiliation: Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Kolkata Mohanpur, West Bengal 741252, India. mvenkataramanan@yahoo.com.
authors.forename: Chanchal
authors.initials: C
authors.lastname: Hazra
authors.forename: Tuhin
authors.initials: T
authors.lastname: Samanta
authors.forename: Aswin Vijai
authors.initials: AV
authors.lastname: Asaithambi
authors.forename: Venkataramanan
authors.initials: V
authors.lastname: Mahalingam