SHINERS for the Study of Electrochemical and Catalytic Processes

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Shell isolated nanoparticle enhanced Raman spectroscopy (SHINERS) is a highly useful and sensitive spectroscopic characterisation tool that allows us not only to study the structure of a molecule but to follow reactions in situ/operando. In situ/operando analysis allows for reactions and processes to be studied in real time and therefore, for any intermediate species and reactions to be seen. Raman spectroscopy by itself is not sensitive enough to complete detailed analysis of trace amounts of species and intermediates in reactions, often due to small Raman cross sections and limited lifetimes, which lead to weak signals being produced. This leads to difficulty determining what has been observed. Using metal nanoparticles, such as gold, silver, and copper, we can use the surface plasmon resonance phenomenon to enhance the signals being detected. By covering these nanoparticles in a very thin (2-4 nm) inert layer, such as SiO2 or Al-2O3, they become shell isolated nanoparticles (SHINs). This allows for the enhancing effect of the metal nanoparticles to be utilised without having an effect on the reaction, process, or molecule being studied. SHINERS show great potential for use in the in situ study of catalytic processes that use transition metals, as the SHINs will not interfere with the process and can therefore provide insight into the often complex reactions taking place. SHINERS also allow for electrochemical processes to be studied in situ for these reasons. In this research endeavour, gold nanoparticles will be encased in an inert layer of SiO2 or Al2O3 to study the catalytic process of aldehyde hydrogenation using platinum and copper via Raman spectroscopy. These shell isolated gold nanoparticles will also be used to study processes occurring on and the degradation mechanism of battery electrodes. This research will be done in conjunction with Johnson-Matthey PLC.