Effective organic amine detection by nanoparticle-assembled tin dioxide microspheres: The importance of interparticle porosity on sensing properties

Organic amines are a kind of industrially important starting material for the manufacture of dyes and pharmaceuticals. But monitoring low-concentration amine vapors, especially those with a high molecular weight, is still a challenging task during industrial processes because the low permeability and diffusivity of amines largely limit their interaction with the surface of sensing element. Herein, we report the template-free solvothermal synthesis of uniform nanoparticle-assembled SnO2 microspheres with an rich interparticle porosity, and the thermal-driven tuning of their porosity structure with the sphere-like morphological preservation. This further allows us to fabricate a sensing film with a tunable interparticle porosity structure and an optimized gas diffusivity in the sensing film. As a result, the optimized SnO2 sensing film is shown to have the ability to effectively detect low-concentration amine vapors with short response time and high response value in the testing range from 1 to 200 ppm.