LUMINESCENT NANOCRYSTALS : APPLICATION AS NANOTHERMOMETERS AND CARACTERISATION OF A PHOTOCATALYSIS REACTOR

Work package:
Context : This internship will be carried out within the framework of a larger project entitled Together-for-CO2, with contributions from laboratories from Toulouse (LCC, LPCNO, Softmat), Strasbourg (ICPEES), and Marseille (Institut Fresnel). The overall objective of Together-for-CO2 is to shed light on some of the processes at play during the photocatalytic transformation of CO2 into methane. This reaction is enhanced in the presence of nanoparticles of noble metal, especially when they are near the TiO2 catalyst. Absorption of visible light by the plasmonic nanoparticles leads to an elevation of the local temperature. We wish to investigate which part of the increased yieldin CH4 can be attributed to the increased temperature. Objectives: In this internship, we wish to carry out temperature measurements by a novel methodology, which makes use of luminescent nanoparticles (NPs), excited in the near infrared and emitting in the visible. In these particles, the relative intensities of the various emission bands depend directly on temperature. By studying them carefully, we can thus deduce temperature from their luminescence profile. The luminescence mechanism of these NPs is known as energy transfer upconversion and requires the NPs to be doped with specific lanthanide ions, with very precise doping levels. The selected candidate will carry out the syntheses of these NPs (diameter ~20 nm, see figure) using methods that are well established at Softmat lab. Caracterisation methods will include standard materials science techniques including X-ray diffraction, transmission electron microscopy and TGA, as well as spectroscopic techniques, such as fluorimetry in upconversion mode. Nanothermometry experiments will also be performed in order to qualify the nanothermometers. Eventually, we will attempt to caracterise the temperature landscape in the photocatalytic reactor.