One-dimensional In2O3 nanofibers patterned onto functionalized catalytic electrodes: A novel approach for selective xylene detection

Remarkable efforts have been devoted for enhancing gas selectivity of chemiresistors via tuning the sensing materials. However, the selective detection of low reactive gases remains challenging. Herein, we report a new strategy for selective detection of low reactive gases by patterning nanofibers and tuning the catalytic property of electrode. In this approach, straight single In2O3 nanofibers are patterned onto Au, Pt, and ITO interdigitated electrodes (IDEs) via direct-write near-field electrospinning; the resulting low coverage of the sensing materials (∼0.12%) exposes the electrode to analyte gases. The gas sensing characteristics of the sensors are determined by the catalytic activity of each electrode. Furthermore, the functionalization of Pt IDE with Au nanoparticles could achieve extremely high selectivity and response toward xylene. The sensing properties and mechanisms of the nanopatterned sensors are investigated regarding electrode composition, degree of electrode exposure, and catalyst location on the electrode and/or sensing materials. The key strategies for achieving high selectivity are the conversion of low reactive xylene gas into more reactive intermediate species while highly reactive interference gases are completely oxidized at open catalytic electrodes. Catalyst functionalization and exposure of electrodes can provide new guidelines for designing high performance gas sensors for new applications.