Graphene-TiS$_3$ heterojunction for selective polar vapor sensing at room temperature

TL;DR

This study demonstrates a room-temperature polar vapor sensor using a Graphene-TiS3 heterojunction, showing high selectivity and rapid response to low ethanol vapor concentrations through 2D material interactions.

Contribution

It introduces a novel 2D heterojunction sensor design that achieves selective, stable, and rapid ethanol vapor detection at room temperature.

Findings

High sensing response (~3353%) at 2 ppm ethanol vapor

Transient response and recovery times around 6 s and 40 s

Selective detection of ethanol vapor at room temperature

Abstract

In this work, the room temperature polar vapor sensing behavior of two dimentional (2D) heterojunction Graphene-TiS3 materials and TiS3 nanoribbons is investigated. TiS3 nanoribbons were synthesized via chemical vapor transport (CVT) and their structure was investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X- ray spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) analysis. The gas sensing performance of the TiS3 nanoribbons was assessed through the observed changes in their electronic behavior. Sensing devices were fabricated with gold contacts and with lithographically patterned graphene (Gr) electrodes in a 2D heterojunction Gr-TiS3-Gr architecture.. It is observed that the gold contacted TiS3 device has a rather linear I-V behavior while the Gr-TiS3-Gr heterojunction forms a contact with a higher Schottky barrier (250 meV). I-V responses of the sensors were recorded at room temperature with a relative humidity of 55% and for different ethanol vapor concentrations (varying from 2 to 20 ppm). I-V plots indicated an increase in the resistance of Gr-TiS3-Gr by the adsorption of water and ethanol molecules with relatively high sensing response (~3353% at 2 ppm). Our results reveal that selective and stable responses to a low concentration of ethanol vapor (2 ppm) can be achieved at room temperature with transient response and recovery times of around 6 s and 40 s, respectively. Our proposed design demonstrate a new approach for selective molecular recognition using polar interactions between analyte vapors and heterojunctions of 2D-materials.