Two novel and high-efficiency optical chemosensors of detecting Fe3+ and CrO42− based on Metal−organic frameworks of Cd(Ⅱ)

Ultrasound-assisted synthesis of europium doped BPO4 nanoparticles; a new approach for Zn2+ (aq) detection

In this work, europium ion was doped into boron phosphate nanoparticles (BPO₄) using an ultrasonic method followed by the calcination process. The nanoparticles were characterized by various techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM). Doping of europium ion into the BPO₄ host crystal was proved by cell volume calculation from XRD patterns, the shift in Raman spectra, and photoluminescence properties. In addition, the europium doped boron phosphate (BPE) as a fluorescence sensor for the quantification of Zn²⁺ cation was studied. The obtained results showed the enhancement and shift of the photoluminescence peak from 292 to 340 nm. The sensor's selectivity toward this ion was verified in the presence of a variety of common interfering cations. Surprisingly, BPE revealed excellent selectivity and sensitivity towards Zn²⁺ in the presence of Pb²⁺, Na⁺, Fe²⁺, Al³⁺, Ca²⁺, Mg²⁺, Cu²⁺, Co²⁺, Ni²⁺, Mn²⁺, Cd²⁺, Hg²⁺, Ba²⁺ and Fe³⁺ cations. The fluorescence response was linearly proportional to the Zn²⁺concentration. After the addition of trace amounts of Zn²⁺ ions into the aqueous solution, a significant enhancement of fluorescence emission occurred with the detection limit of 0.3 μM.