Ratiometric fluorescence determination of hydrogen peroxide using carbon dot-embedded Ag@EuWO4(OH) nanocomposites.

A sheet-like carbon dot-embedded Ag@EuWO4(OH) luminescent nanoprobe was successfully developed for assaying hydrogen peroxide. Firstly, the carbon dot-embedded EuWO4(OH) nanosheets were prepared in a Eu(NO3)3·6H2O-(NH4)10H2(W2O7)6·xH2O-CS(NH2)2 hydrothermal synthetic system. Subsequently, the carbon dot-embedded EuWO4(OH) was functionalized by Ag nanoparticles using an in situ photochemical deposition strategy upon ultraviolet light irradiation. Taking advantage of the dual emissions of the luminescence from carbon dots and characteristic red transitions of Eu3+ ions in the integrated system, the carbon dot-embedded Ag@EuWO4(OH) luminescent composites exhibit ratiometric fluorescence responsive activity towards hydrogen peroxide. The luminescent intensity ratio of Eu3+ (614 nm) to carbon dots (389 nm) shows a polynomial function with changing hydrogen peroxide concentration. The corresponding detection limit is 60 μM at a signal-to-noise ratio of 3 (S/N = 3) implying the potential use of the carbon dot-embedded Ag@EuWO4(OH) as nanoprobe. The method was applied to the quantification of H2O2 in real samples with satisfactory results. Graphical abstract A carbon dot-embedded Ag@EuWO4(OH) luminescence ratiometric probe was successfully prepared through hydrothermal method and in situ photochemical deposition strategy. The luminescence intensity ratio of Eu3+ to carbon dots shows synergistic luminescence response activity towards H2O2 with detection limit of 60 μM.