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In situ transmission electron microscopy provides exciting opportunities to address fundamental questions and technological aspects related to functional nanomaterials, including the structure-property relationships of miniaturized electronic devices. Herein, we report the in situ chemoresistive sensing in the environmental transmission electron microscope (TEM) with a single SnO nanowire device, studying the impact of surface functionalization with heterogeneous nanocatalysts. By detecting toxic carbon monoxide (CO) gas at ppm-level concentrations inside the microscope column, the sensing properties of a single SnO nanowire were characterized before and after decoration with hybrid Fe-Pd nanocubes. The structural changes of the supported nanoparticles induced by sensor operation were revealed, enabling direct correlation with CO sensing properties. Our novel approach is applicable for a broad range of functional nanomaterials and paves the way for future studies on the relationship between chemoresistive properties and nanoscale morphology.

We report in situ and ex situ fabrication approaches to construct p-type (CuO) and n-type (SnO2) metal oxide nanowire devices for operation inside an environmental transmission electron microscope (TEM). By taking advantage of their chemoresistive properties, the nanowire devices were employed as sensitive probes for detecting reactive species induced by the interactions of high-energy electrons with surrounding gas molecules, in particular, for the case of O2 gas pressures up to 20 mbar. In order to rationalize our experimental findings, a computational model based on the particle-in-cell method was implemented to calculate the spatial distributions of scattered electrons and ionized oxygen species in the environmental TEM. Our approach enables the a priori identification and qualitative measurement of undesirable beam effects, paving the way for future developments related to their mitigation.

SnO2-based chemoresistive sensors integrated in complementary metal-oxide-semiconductor technology were functionalized with ultrasmall Pt nanoparticles, resulting in carbon monoxide sensing properties with minimized humidity interference.

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