Plasmas in direct contact with liquids or plasmas inside liquids allow a high mass transfer of reactive species from the gas phase into the liquid. If these plasmas in liquids are interfaced with solids, very fast and efficient reaction rates for surface reactions can be realised. Such systems are relevant for the field of degradation of toxic organic compounds in liquids, plasma enhanced anodisation of metal surfaces inside an electrolyte, or as a method to recover a catalytic surface in an electrochemical cell. In this project, FTIR spectroscopy in the attenuated reflection mode will be used to probe the plasma-liquid-solid interface directly. The liquid chemistry is assessed using optical absorption spectroscopy in the visible spectral range. This method is employed to analyse aluminium oxide that is created during plasma enhanced oxidation (PEO) in a liquid.
By monitoring the different oxygen bonds, the progress of the anodisation process is monitored. Similar, the degradation of an oxidized copper surface used as catalyst for CO2 dissociation in an electrochemical cell is monitored in-operando. By striking a plasma at the liquid-solid interface, the recovery of the catalyst surface is monitored. Finally, the influence of in-liquid-plasma on the efficiency of a biocatalyst is evaluated. In all these experiments, the effects on the surface and in the plasma can be separated, because the broad absorption features of the TO and LO phonon of the metal oxides can easily be distinguished from the narrow absorption bands of the free gas molecule created in the plasmas. The reaction sequences at the plasma-liquid-solid interface are elucidated by connecting the variation of the surface processes, with that of the plasma chemistry.
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copyright 2018 | SFB 1316 | Transient Atmospheric Pressure Plasmas - From Plasmas to Liquids to Solids