| AVS 60th International Symposium and Exhibition | |
| Nanometer-scale Science and Technology | Monday Sessions |
| Session NS+AS+EM-MoA |
| Session: | Nanowires and Nanotubes |
| Presenter: | E. Stuckert, Colorado State University |
| Authors: | E. Stuckert, Colorado State University E.R. Fisher, Colorado State University |
| Correspondent: | Click to Email |
As toxic gases like NOx, benzene, and formaldehyde continue to be emitted globally, their negative impacts on people’s health persist. With gases capable of causing harm on the part per billion level, it is critical to accurately sense toxic gases in real time. This requires creating sensors that operate at lower temperatures, are more sensitive, and are more selective for sensing a desired gas than what is commercially available. SnO2 is commonly used to create sensing materials because it has enhanced gas-surface interactions as a result of its variable oxidation states, namely Sn2+ and Sn4+. Plasma modification is one method of altering the SnO2 surface to enhance sensitivity and selectivity. The plasma treatments create more surface oxygen vacancies in the SnO2, which allows for increased sites for atmospheric oxygen to adsorb. The sorption of gases is highly dependent on the predominant oxygen species on the sensor surface at a given plasma treatment and temperature. Our results demonstrate that SnO2 nanowires grown by chemical vapor deposition (CVD) and commercial SnO2 nanoparticles treated in Ar/O2 plasmas have lattice oxygen removed from the surface. Removal of surface oxygen is corroborated through X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). XPS data show that low plasma power treatments (10-60 W) alter the surface oxygen composition of SnO2 nanowires and nanoparticles, with the maximum change in composition peaking at 30 W. More importantly, the oxygen vacancies in the treated nanowires are significantly higher than those observed for treated nanoparticles. In addition to surface analysis results, resistance of SnO2 nanowire and nanoparticle sensors when exposed to a range of gases (i.e., methanol, ethanol, propanol, benzene, and formaldehyde) is used to explore specific gas-surface interactions. By relating plasma treatment conditions to the resulting surface composition and the sensor’s response upon exposure to gases, insight into how surface modification affects gas-surface interactions in sensors will be presented.
Keywords:
Plasma modification, Gas sensor, Tin oxide, Nanowire, Nanoparticle