The detection of gaseous oxygen (O2) in gas mixtures is relevant for air quality control, packaging, life sciences, automotive industry, and chemical industry. Starting from previous literature results on the ability of TiO2 nanostructures to act as a photoluminescence-based probe of O2, in this work we explored the possibility to produce a mesoporous mixed-phase TiO2 by using a metal organic framework (MOF) as sacrificial template and to test it as dual-emitting O2 optical probe. Mesoporous TiO2 containing both anatase and rutile crystalline phases was produced starting from a 1,4-benzenedicarboxylate (BDC)-based MOF containing Ti as metallic center (MIL125-(Ti)). Two different calcination temperatures were explored with the aim of modulating the ratio between the two crystalline phases. The obtained samples were characterized by TGA, SEM, HRTEM, N2 adsorption- desorption isotherms, XRD, FTIR, XPS and photoluminescence (PL) spectroscopies. Their capacity to act as doubly-parametric O2 optical sensor was evaluated by measuring PL intensity changes during O2 exposure (Fig.1). In particular, the time dynamics of the PL modulation for VIS-PL and NIR-PL emission bands were investigated by measuring PL spectra during exposure to flowing Air-N2 mixtures at different relative concentrations. The results showed that the MOF-derived samples exhibited responses to air densities in the 2-20% range. Future work will be focused on the detection of lower concentrations of O2 and to improve the responsivity of both NIR- and VIS-PL components also by metal doping.
Mixed-phase TiO2 obtained through MOF mediated synthesis (MOFMS) for doubly-parametric O2 optical sensor development
V Gargiulo;S Lettieri;
2022
Abstract
The detection of gaseous oxygen (O2) in gas mixtures is relevant for air quality control, packaging, life sciences, automotive industry, and chemical industry. Starting from previous literature results on the ability of TiO2 nanostructures to act as a photoluminescence-based probe of O2, in this work we explored the possibility to produce a mesoporous mixed-phase TiO2 by using a metal organic framework (MOF) as sacrificial template and to test it as dual-emitting O2 optical probe. Mesoporous TiO2 containing both anatase and rutile crystalline phases was produced starting from a 1,4-benzenedicarboxylate (BDC)-based MOF containing Ti as metallic center (MIL125-(Ti)). Two different calcination temperatures were explored with the aim of modulating the ratio between the two crystalline phases. The obtained samples were characterized by TGA, SEM, HRTEM, N2 adsorption- desorption isotherms, XRD, FTIR, XPS and photoluminescence (PL) spectroscopies. Their capacity to act as doubly-parametric O2 optical sensor was evaluated by measuring PL intensity changes during O2 exposure (Fig.1). In particular, the time dynamics of the PL modulation for VIS-PL and NIR-PL emission bands were investigated by measuring PL spectra during exposure to flowing Air-N2 mixtures at different relative concentrations. The results showed that the MOF-derived samples exhibited responses to air densities in the 2-20% range. Future work will be focused on the detection of lower concentrations of O2 and to improve the responsivity of both NIR- and VIS-PL components also by metal doping.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
