Hydrothermal synthesis of arginine decorated NaxLiyPr(MoO4)2:Tb3+ and NaxLiyPr(WO4)2:Tb3+ nanomaterials: photocatalytic degradation and luminescent sensing of picric acid in an aqueous medium†

Abstract

Many common explosives are mostly composed of nitro-compounds. Picric acid (PA) has emerged as a potential alternative due to its great explosive capability. Moreover, PA is also a serious groundwater contaminant due to its high-water solubility. As a result, the development of advanced sensors and catalysts to enable the precise detection and elimination of PA in water and food samples is critical for public health and the environment. In the present investigation, we developed Na_xLi_yPr(MoO₄)₂:Tb³⁺@Arg and Na_xLi_yPr(WO₄)₂:Tb³⁺@Arg (x = 10 mmol and y = 5 mmol) via a hydrothermal process and established their potency for photoluminescence (PL) detection and photocatalytic degradation of PA. The characterization of the produced nanoparticles was done by various techniques. The PL characteristics of Na_xLi_yPr(MoO₄)₂:Tb³⁺@Arg show that it is highly sensitive and selectively detects PA in an aqueous medium. The predominant emission band at 545 nm exhibited a distinguished quenching with the introduction of PA solution in the colloidal solution of the prepared nanomaterials. The Na_xLi_yPr(MoO₄)₂:Tb³⁺@Arg demonstrated exceptional selectivity and sensitivity against PA, with a limit of detection (LOD) of 0.44 ppm and a quenching constant (K_SV) of 2.74 × 10⁴ M⁻¹. Alternatively, the Na_xLi_yPr(WO₄)₂:Tb³⁺@Arg showed remarkable photocatalytic activity for PA degradation. The UV-Vis spectroscopy findings specify that Na_xLi_yPr(WO₄)₂:Tb³⁺@Arg (E_g = 2.95 eV) might operate as a superior photocatalyst compared to Na_xLi_yPr(MoO₄)₂:Tb³⁺@Arg (E_g = 3.38 eV) nanoparticles. The degradation efficacy of Na_xLi_yPr(WO₄)₂:Tb³⁺@Arg towards PA is around 96.7% within 60 minutes of UV irradiation and the photocatalyst's reusability was monitored to ensure good stability. This remarkable photocatalytic activity of Na_xLi_yPr(WO₄)₂:Tb³⁺@Arg was ascribed to increased migration efficiency of photo-generated electrons and holes.