Vertically Aligned Porous V<sub><i>x</i></sub>O<sub><i>y</i></sub> Nanofilms with Pt Decoration for Sub-ppm H<sub>2</sub> Gas Sensors
Jyoti Jaiswal, Abhijeet Das, Vivek Chetry, Sanjeev Kumar, Ramesh Chandra, Kazuyoshi Tsuchiya
Abstract
Due to poor selectivity, existing H 2 sensors based on metal oxide semiconductor (MOS) nanostructures do not perform well at low concentrations. In this report, we have developed an improved sub-ppm H 2 gas sensor based on Pt-decorated vertically aligned porous V x O y nanofilms (Pt/V x O y ) using the magnetron sputtering technique. The field emission scanning electron microscopy studies revealed that the as-grown V x O y nanofilms are vertically aligned with porous surface structures that are cross-linked. High-resolution transmission electron microscopy image results endorsed the growth of isolated island-like Pt nanoparticles (average size of ∼3.7 ± 0.2 nm). Our X-ray photoelectron spectrophotometry and XRD analyses confirmed the oxidation state and phase of the as-deposited V x O y nanofilm, which consisted of orthorhombic-V 2 O 5 with orthorhombic-VO 2 inclusions. The Pt/V x O y nanofilm sensors exhibited high sensing response (99.59%) combined with fast response time (7 s) and short recovery time (18 s) to 100 ppm H 2 at 150 °C temperature compared to pristine V x O y (response ∼28.55% and response/recovery time ∼50 s/110 s). Also at room temperature, the Pt/V x O y nanofilm sensor exhibited a far better H 2 -sensing response of 9.65% compared to 1.13% response of pristine V x O y . In addition, we performed elaborate studies to test the selectivity, repeatability, and durability of the Pt/V x O y nanofilm sensors. With improved sensitivity and selectivity, our fabricated sensor allows the detection of trace-level H 2 with an estimated limit of detection value of 97 ppb.