Colloidal InSe nanostructures: Effect of morphology on their chemical sensitivity to methanol and formaldehyde fumes

Herein we report for the first time, on the synthesis and characterization of indium monoselenide nanoparticles and nanosheets and their application as chemical sensors. We investigate the effect of the different morphologies on methanol and formaldehyde sensing. The synthesized nanostructures crystallized in the same phase however the different morphologies had an influence in the optical properties with the nanoparticles more blue shifted from bulk. As sensing ability is related to the electronic structure, it was palpable that the different morphologies will bring about different results. The sensor fabricated using the InSe nanoparticles gave a good response to methanol fumes and responded to formaldehyde vapour and was selective to formaldehyde than chloroform and acetone. The sensors fabricated using the InSe nanosheets also gave a good response towards formaldehyde; however the sensor recovered half way. For the methanol detection using a similar device, the noise to signal ratio was relatively high. The operating temperature range for the InSe sensor devices were determined to be near room temperature. The sensors response was observed to decrease with increasing temperature from 30 to 90 °C. Evident from the results, the surface capping molecule (oleylamine) employed to stabilize the nanostructures during synthesis was responsible for the poor sensing abilities of the nanostructures.