Microscopic mechanisms of luminescence quenching in Eu3+-doped 3+-doped GdVO4 4 nanoparticles under hydrogen peroxide decomposition

Sensing intracellular level of hydrogen peroxide (H2O2) 2 O 2 ) is an extremely important task, because the overproduction of H2O2 2 O 2 causes cell mutations and the development of various pathologies. Eu3+-doped 3+-doped GdVO4 4 NPs has a great potential as multifunctional theranostic agent, as well as a sensor of intracellular H2O2. 2 O 2 . Therefore, detailed studies of all factors affecting their catalytic and luminescence properties, including the impact of H2O2 2 O 2 on their luminescent properties, are required. In present study, we have analyzed the effects of H2O2 2 O 2 on Eu3+ 3+ luminescence intensity in GdVO4:Eu3+ 4 :Eu 3+ NPs synthesized in a water solution. As-synthesized NPs were characterized by XRD, HR-TEM, XPS and optical spectroscopy techniques. To analyze the surface modification of GdVO4:Eu3+ 4 :Eu 3+ NPs after H2O2 2 O 2 exposure, XPS analysis and time-resolved luminescence spectroscopy were also used. Two mechanisms responsible for the observed Eu3+ 3+ luminescence quenching in GdVO4:Eu3+ 4 :Eu 3+ NPs were found: (i) the decrease in the efficiency of non-radiative resonance energy transfer through the vanadate VO 3- 4 groups to Eu3+ 3+ ions due to the scattering effect of V 4+ ions and (ii) the direct quenching of Eu3+ 3+ luminescence by -OH groups formed at the surface of NPs as a result of H2O2 2 O 2 decomposition.