Blueberry Anthocyanin Functionalized CaMoO₄:Tb³⁺ Nanophosphors for Dual-Mode pH Sensing

A series of green phosphors, Ca_1-y%MoO₄:y%Tb³⁺ (where y = 0.1, 0.5, 1, 2, 3, 4, and 5) were successfully prepared via hydrothermal synthesis. The pH levels were used to modulate the luminescent of CMO:Tb. To confirm the potential application of proposed phosphors, Blueberry anthocyanin (BBA) was loading onto CMO:Tb surface to form a luminescence probe. The synthesized phosphors and probes were characterized using X-ray diffraction (XRD), FT-IR spectra, transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). As a proof-of-concept, the constructed probes were adopted to evaluate the acidity of solution. The results showed that luminescence emission intensity at 546 nm increased with pH value increasing in the range of 2-12. Meanwhile, the color of the sensor solution changed from bright red to pink, then to purple, and finally to yellow as the pH varies between 2 and 12. The above results indicated that the proposed probe could evaluate the acidity of solution via the dual-mode luminescence detecting and naked eye to obtain accurate results. This proposed strategy gives an insight to design the efficient probes to precisely and sensitively evaluate the acidity in complex samples.