A novel N/Au co-doped carbon dot probe for continuous detection of silicate and phosphate by resonance Rayleigh scattering

Abstract

Co-doped carbon dots are new multifunctional carbon nanomaterials. Their fast preparation and new analytical applications such as in continuous detection and resonance Rayleigh scattering (RRS) probes are of interest to people. Herein, the N/Au co-doped carbon dots (CD_N/Au) were prepared quickly by a microwave synthesis method using fructose as the carbon source and urea and HAuCl₄ as dopants, and it exhibited an excellent RRS effect at 555 nm. Based on both silicate (SiO₃²⁻) and phosphate (PO₄³⁻) reacting with ammonium molybdate to form silicomolybdate heteropoly acid (SiMo) and phosphomolybdate heteropoly acid (PMo), PMo decomposed by the addition of citric acid, and SiMo/PMo combined with CD_N/Au to show good RRS analytical properties, and a new strategy was developed to detect SiO₃²⁻ and PO₄³⁻ by the CD_N/Au probes continuously. With the increase of SiO₃²⁻ (PO₄³⁻), SiMo (PMo) reacted with CD_N/Au probes to form more big particles which resulted in the RRS intensity enhancement at 555 nm, and had a good linear relationship with the SiO₃²⁻ (PO₄³⁻) concentration in the range of 1.11 μg L⁻¹–19.98 μg L⁻¹, with detection limits of 0.3 μg L⁻¹ SiO₃²⁻ and 0.3 μg L⁻¹ PO₄³⁻. Accordingly, a new RRS method was established for continuous detection of SiO₃²⁻ and PO₄³⁻ using CD_N/Au as the probe.