Effect of Hydrogen Peroxide Decomposition on Luminescence and Microstructure of GdVO₄:Eu³⁺ Redox-Active Nanocrystals

In the present study, we investigated the effects of hydrogen peroxide on $\mathbf{E u}^{3+}$ luminescence quenching and microstructure of GdVO4: $\mathbf{E u}^{3+}$ nanocrystals synthesized in an aqueous solution. The obtained nanocrystals were characterized using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and optical spectroscopy techniques. Two mechanisms responsible for the observed $\mathrm{Eu}^{3+}$ luminescence quenching were identified: reduced efficiency of non-radiative resonance energy transfer from vanadate ($\mathrm{VO}_{4}{ }^{3-}$) groups to $\mathrm{Eu}^{3+}$ ions due to reducing of vanadium ions and direct quenching of $\mathbf{E u}^{3+}$ luminescence by $\mathrm{OH}^{-}$groups formed on the surface as a result of hydrogen peroxide decomposition. This study enhances our understanding of how hydrogen peroxide influences the luminescent properties and surface microstructure modifications of GdVO $_{4}: \mathrm{Eu}^{3+}$ nanocrystals, thereby contributing to their potential as effective intracellular hydrogen peroxide sensors.