Investigation of the Interaction of Pyridine Complexes and MoS$_{\mathrm{2}}$ Nanoflakes via Raman Spectroscopy

Monitoring chemical reactions in real time has applications ranging from basic chemical analysis of intermediates to catalysis to biochemistry. Raman spectroscopy is a highly selective sensing technique that can give detailed chemical information about an analyte in real time. In this work, we investigate the chemical activity of MoS$_{\mathrm{2}}$ nanoflakes using Raman spectroscopy. Pyridine is used as a Raman probe due to its well-known vibrational spectrum. When mixed with ethanol or water, pyridine forms complexes via hydrogen bonding that shift the Raman peaks in a quantifiable manner. By mixing these complexes with prepared solutions of MoS$_{\mathrm{2}}$ nanoflakes, the effect of the nanoparticles on the interaction of pyridine and its solvent can be measured. Peak ratio analysis indicates that smaller flakes seem to ``accelerate'' the interaction, creating larger peak shifts at much lower concentrations of nanoflakes. This is likely due to the increased ratio of edge sites to surface area of the flakes.