Formation of Ru catalytic nanoparticles onto polyethylene glycol by plasma sputtering
Résumé
Development of metallic nanoparticles (NPs) materials with high catalytic and electrocatalytic potential by using innovative methods is essential for hydrogen storage. For this application, we synthesized Ru metal NPs in polyethylene glycol (PEG) by the sputtering on liquid (SoL) method, which is a favorable technique for the synthesis of ultra-pure NPs, halfway between the physical and chemical methods. Therefore, this process does not require an additional stabilisation step, while still being capable of synthesising NPs of controlled size, shape and purity. The initial step of this study focuses on the diagnostic of the plasma phase by means of optical emission spectroscopy (OES). This allows for highlighting particularly the plasma/liquid interactions by showing the presence of excited species originating from the liquid, such as OH and Hα. Line emissions of excited Ru and Ar are also observed. Then, the PEG+NPs solution was characterized by various methods in order to verify the presence of nanoparticles and to determine their characteristics such as their morphology, concentration, size and size distribution as a function of the plasma generating power, the amount of liquid and the temperature of the latter. UV-Vis-NIR spectroscopy shows metallic or semi-metallic behaviour of the PEG+NPs solution, with the amount of NPs depending on the sputtering conditions. The main results of HRTEM and SAXS analysis show that the Ru NPs have a diameter of 2-5nm, but can aggregate to form larger particles during or after deposition, depending on both the sputtering conditions and the liquid characteristics.