Temperature-dependent Raman spectroscopy and sensor applications of PtSe₂ nanosheets synthesized by wet chemistry

We report on a wet chemistry method used to grow PtSe₂ nanosheets followed by thermal annealing. The SEM and TEM analysis confirms the formation of PtSe₂ nanosheets. Furthermore, XRD, Raman, XPS and SAED patterns were used to analyze the crystal structure and to confirm the formation of the PtSe₂ phase. The temperature-dependent Raman spectroscopy investigations were carried out on PtSe₂ nanosheets deposited on Si substrates in the temperature range 100-506 K. The shifts in Raman active E_g and A_1g modes as a function of temperature were monitored. The temperature coefficient for both modes was calculated and was found to match well with the reported 2D transition metal dichalcogenides. A PtSe₂ nanosheet-based sensor device was tested for its applicability as a humidity sensor and photodetector. The humidity sensor based on PtSe₂ nanosheets showed an excellent recovery time of ≈5 s, indicating the great potential of PtSe₂ for future sensor devices.