Strong UV Emission from Colloidal Eu²⁺‐Doped BaSO₄ Nanoparticles: A Material for Enhancing the Photocatalytic Activity of Carbon Dots

Abstract

In this article, we report a facile microwave‐assisted green synthetic route for the preparation of highly luminescent water dispersible polyacrylic acid‐coated europium (Eu2+)‐doped BaSO4 nanoparticles at low temperature for the first time. Polyacrylic acid coating over nanoparticles renders them water dispersible. Upon ultraviolet (UV) (250 nm) excitation, europium‐doped BaSO4 nanoparticles exhibit a strong and broad UV luminescence near at 368 nm. This emission peak is quite strong and has a relative luminescence quantum yield (QY) of 53 %. The high QY of the UV emission from the nanoparticles is explored for the enhancement of the visible photocatalytic properties of the carbon dots (Cdots). In fact, faster degradation of the Rhodamine B is noted for the mixture containing both Eu2+‐doped BaSO4 nanoparticles and cetyl trimethylamonium bromide capped carbon dots. This is attributed to the strong overlap of the UV emission of Eu2+ with the absorption spectrum of Cdots leading to high energy transfer efficiency (∼64 %). The energy transfer process is supported by the observation of lower dye degradation for the diluted colloidal mixtures where the average distance between Eu2+ in BaSO4 to Cdots nanoparticles is increased.

Defect induced “super mop” like behaviour of Eu3+-doped hierarchical Bi2SiO5nanoparticles for improved catalytic and adsorptive behaviour

“…38 In one of our previous articles, we have observed that ethylene glycol is capable of reducing Eu 3+ into Eu 2+ at high temperatures. 39 Therefore, we believe that the usage of ethylene glycol during synthesis is responsible for the partial reduction of Eu 3+ into Eu 2+ in the as-prepared Eu-BSO materials. The effect of the formation of Eu 2+ is also reflected in the O 1s spectrum as shown in Fig.…”

Design of Lanthanide-Doped Colloidal Nanocrystals: Applications as Phosphors, Sensors, and Photocatalysts

“…Interestingly, Eu 2+ ions are known to undergo a downshifting process (i.e., they absorb in the UV region (250 nm) and emit at ∼368 nm, which in turn is the absorption region of C dots that has been reported to be an efficient photocatalyst). Polyacrylic acid-coated Eu 2+ -doped BaSO 4 nanocrystals and CTAB-capped C dots were synthesized by a microwave technique . While the separate use of Eu 2+ -doped BaSO 4 nanocrystals and C dots degrades rhodamine B in an aqueous solution under irradiation bore no fruitful results, excellent photocatalytic activity was observed when they were used together (95% in 3 h; rate constant, 0.0142 min –1 ).…”

“…Polyacrylic acid-coated Eu 2+ -doped BaSO 4 nanocrystals and CTAB-capped C dots were synthesized by a microwave technique. 122 While the separate use of Eu 2+doped BaSO 4 nanocrystals and C dots degrades rhodamine B in an aqueous solution under irradiation bore no fruitful results, excellent photocatalytic activity was observed when they were used together (95% in 3 h; rate constant, 0.0142 min −1 ). The results indicate that upon UV excitation the Eu 2+ present in BaSO 4 nanocrystals efficiently transfers energy to C dots, which in turn degrades organic pollutants.…”

Hierarchical electrostatic nanotemplating and self-assembly of electron-transferring hybrid nanostructures: CdS–polymer–porphyrin particles

“…50 This benefit is also valid for the dye degradation where current systems still rely strongly on the UV-light excitation. 51–53 Those systems might also profit from using photosensitizers, which – following the principle introduced herein – can be built in hierarchically after synthesis.…”