Description du sujet de thèse

Robust and Reusable plasmonic photoelectrochemical electrodes: individual nanoprobes in liquid phase.

Among the numerous environmental and societal issues the world is facing nowadays, air and water pollution are of major concerns. In that context, the development of novel, rapid and highly sensitive detection techniques becomes crucial. In this respect, metallic nanoparticles (MNPs) have been shown to be sensitive optical sensors thanks to their localized surface plasmon resonance (LSPR) whose characteristics depend on their composition and morphology (shape and size), but also on their local environment. More specifically gold nano-bipyramids (AuBPs) are very promising candidates as they display an LSPR with a high quality factor and thus a strong sensitivity to the environment (see Figure).
Our project aims to develop a device allowing the detection, in dynamic regime and with a high sensitivity, of polluting substances like heavy ions in liquid environment. The technology will be based on an electrochemically triggered plasmonic detection allowing the real time monitoring of various physico-chemical processes at the scale of the single nanoparticle and on time scales allowing the realization of broadband spectra on times of a few seconds, thus allowing the monitoring of the reaction kinetics by plasmonic spectroscopy.

Contexte de travail

The thesis will be hosted at the Institut Lumière Matière (ILM) in Villeurbanne. The Institut Lumière Matière (iLM) is a CNRS-Université Lyon 1 research unit located on the Lyon Tech La Doua campus. With around 300 employees, including a hundred PhD and post-doctoral students, and 150 trainees per year, the iLM is a major player in physics and chemistry research in the Auvergne Rhône Alpes region, internationally recognized for the excellence of its research. The person recruited will be involved in both parts of the project (chemical synthesis and optical spectroscopy). The first part will concern the elaboration of the devices consisting in grafted AuBPs immobilized on a transparent and conducting glass substrate, allowing photo-electrochemical detection of specific heavy metals such as lead, mercury or cobalt. As concerns the optical spectroscopy part, the spatial modulation spectroscopy (SMS) technique in a liquid environment was shown to be highly sensitive to detect small variations of the optical index of the environment of single AuBPs (see Figure). The combination of this SMS technique with electrochemical studies using a potentiostat will be performed without and with a given concentration of heavy metals in the solution. The sensitivity of single AuBPs to detect the presence of heavy metals will then be fully investigated. Thereafter, the possibility to perform dynamic measurements at the single nanoparticle level will be studied.

The candidate should have a master's degree in physics with advanced skills in optics and spectroscopy. A good grounding in nanoparticle chemistry and electrochemistry will be an added advantage.

Contraintes et risques

Techniques/methods in use: optical spectroscopy on single NPs, voltamperometry, NP synthesis, grafting of NPs, electrochemistry
Partnership: Laboratoire de Chimie de Lyon, ICL-ENS Lyon