Postdoctoral position - Sputtering on ionic liquid for nanoparticles synthesis of Bi-based material for CO2 photoconversion application

OPPORTUNITY DETAILS

Total reward

0 $

State University

LabEx IMobS3

Area

Western Europe

Host Country

France

Deadline

19 Aug 2021

Study level

Doctoral Degree

Opportunity type

Post-doctoral

Specialities

Physics , Chemistry

Opportunity funding

Not funding

Eligible Countries

This opportunity is destined for all countries

Eligible Region

All Regions

In the framework of the research project “Innovative systems and services for transport and production” I-SITE CAP 20-25 (Challenge 2), a one-year postdoctoral position is proposed for highly motivated candidates interested in plasma process and material science. The candidate will be joining the Chemistry Institute of Clermont-Ferrand.

Subject

Sputtering on ionic liquid for nanoparticles synthesis of Bi-based material for CO₂ photoconversion application.

Scientific project and objectives

Photocatalysis is more and more extended in energy domain. Indeed, production of green chemical ad solar fuels by photoconversion of CO₂ is considered as a clean energy storage technology with minimal impact to the environment. Some semiconductors, like TiO₂ or ZnO, are widely studied for these applications, but discovering new materials is still the most pivotal topics in this field. Recently, Bismuth-based materials gained huge attention because of their advantages such as low toxicity, low solubility and corrosion resistance. From one hand, Bi nanoparticles decorating a semiconductor are shown to increase the light absorption, thanks to a surface plasmon effect^[^{Appl. Cat. B: Environ., 205, 2017, 532}^], and therefore the photocatalytic efficiency. From the other hand, Bi- sulfides^[^{Nano Res., 3, 2010, 379}^], oxides^{[Appl. Cat. B: Environ., 188, 2016, 87]} or oxyhalides BiOX (X= halogenide)^{[Nanoscale, 6, 2014, 2009]} have been explored as semiconductor and so as potential photocatalyst. Recently, at ICCF in collaboration with IFPEN, we demonstrated that, by changing the O₂ and CF₄ gas flow rates injected during the radiofrequency magnetron sputtering of a Bismuth target, thin film composition of Bi-based materials can be tuned and so their energy band positions can be adapted to the targeted redox potential. Moreover, we succeed to form in one-pot thin film heterojunctions of Bi/Bi₂O₃ and Bi/BiO_xF_y, with photocatalytic activities in pollutant photodegradation and in photoconversion of CO₂ in CO, higher than for Bi-based compounds in powder ^{[Mat. Chem. Phys., 24, 2020, 122580]}. CO is an energy-rich storage molecule, which can further be used to form formic acid (HCOOH), syngas (CO/H₂) and other chemicals. However, the low specific surface area (> 1 m²/g) of our thin films is clearly identified as a major keylock of their further development. To overcome this limitation, we investigated the sputtering on ionic liquid technique. This process was very recently proposed to form spherical nanoparticles, with narrow size distribution (diameter < 20 nm). Such NPs could present a much higher specific surface area (≈ 100 m²/g, e.g. x 100 compared to a flat film) and take advantage of plasmonic effects. However, up to now, this technique was mainly tested to produce metallic (Ti, Ag^{[J. Phys. Chem. C, 122, 2018, 26605]}) or alloy (Ag-Au ^{[Mater. Lett., 171, 2016, 75]}) nanoparticles. In the framework of the PULSION I-SITE project, et based on preliminary tests, the goal of the one-year post-doctoral fellow will be to study the sputtering on ionic liquid in reactive mode, that is to say to inject O₂ and/or CF₄ to form nanoparticles of Bi, BiO_x or BiO_xF_y with controlled composition and to study their photocatalytic properties, especially for CO₂ photoconversion.

The post-doctotoral fellow will be in charge of investigating the plasma / ionic liquid interaction during reactive sputtering in order to control the nanoparticles composition, by exploring the effect of reactive gas flow rates and other various process parameters (power, gas pressure, interelectrode distance…). The Optical Emission Spectroscopy should be for instance used for this. Different ionic liquid could also be tested depending on their properties (hydrophobicity, CO₂ solubilization…). The synthesized nanoparticles (dispersed in ionic liquid or transferred to a foam) will also be studied thanks to the large range of techniques available at ICCF or in Clermont-Ferrand site for characterization of materials (Raman and FTIR spectroscopies, XRD, SAXS, XPS, BET, EPR…) and of their optical and photocatalytic properties.

Moreover, the project could benefit from collaborations with PHOTON Team in Institute Pascal (Clermont-Ferrand), which will try to simulate the electromagnetic properties of these nanostructured materials, IMN (Nantes) for their TEM local characterization, and IFPEN (Solaize) for the evaluation of their CO₂ photoconversion efficiency.

Requirements

The fellow should have an expertise in plasma process and material science. A first experience on nanomaterials would be appreciated. She/he should be highly motivated and enjoy working in a team while demonstrating curiosity, autonomy, dynamism and rigor. The candidate should also have good communication skills in French and English (oral and written). The application form must contain a Curriculum Vitae, a motivation letter, and reference letters.