Utilizing photoactivated ZnO-coated silica nanospring mats for chemical detection*

Detecting ammonium nitrate remains difficult owing to its low vapor pressure. To address this, we are investigating the utility of silica-based nanospring mats coated with zinc oxide as the sensors. We are measuring the electrical responses of the sensors when exposed to heated ammonium nitrate while illuminated with near-UV light source in ambient condition. In general, since the ZnO coated nanosprings have very high surface-to-volume ratio, they offer a wider area for components of ammonium nitrate to interact with oxygen ions in the sensors, thereby making them more sensitive compared to thin films. In addition, illuminating the sensors help in generating electron-hole pairs that would offset the effect of redox processes in their detection capabilities. The generated holes can recombine with the adsorbed O₂ species in the surface and the uncompensated electrons enhance the electrical conductivity. Furthermore, to improve the sensors’ selectivity, we are exploring the usage of functional groups that can attract ammonium nitrate.