Self-heating oxidized suspended Pt nanowire for high performance hydrogen sensor

In this work, joule-self-heating of a suspended Pt nanowire, under oxygen ambient, is utilized to form PtOx/Pt nanostructure to develop a new type of 1-dimensional sensor device architecture for detection of hydrogen at room temperature. An optimum design space for the sensor is elucidated with the initial Pt nanowire thickness ranging between 10 nm and 80 nm. Single PtOx/Pt nanowire sensor, based on optimum metal (Pt) to metal-oxide (PtOx) junction can detect down to 100 ppm H2 with ultra-low power consumption of ∼45 nW. This study also investigates hydrogen sensing characteristics of an array of oxidized Pt nanowires, which enhances the response with the maximum sensitivity of ∼936%, compared to single PtOx/Pt nanowire sensor sensitivity of ∼13% for 100 ppm hydrogen. Nanowire array sensor provides the minimum detection limit of 500 ppb (∼18.1%) with very fast response (∼25 s) and recovery (∼108 s) time. A phenomenological model is proposed to elaborate the nature of oxidation of joule-self-heated Pt nanowire in oxygen ambient.