UV-Light-Tunable p-/n-Type Chemiresistive Gas Sensors Based on Quasi-1D TiS3 Nanoribbons: Detection of Isopropanol at ppm Concentrations

Abstract

The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS3) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS3 nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as well as with heating up to 110 °C, and under an ultraviolet (UV) radiation at λ = 345 nm. We found that the RT/UV conditions result in a n-type chemiresistive response to isopropanol, which seems to be governed by its redox reactions with chemisorbed oxygen species. In contrast, the RT conditions without a UV exposure produced a p-type response that is possibly caused by the enhancement of the electron transport scattering due to the analyte adsorption. By analyzing the vector signal from the entire on-chip multisensor array, we could distinguish isopropanol from benzene, both of which produced similar responses on individual sensors. We found that the heating up to 110 °C reduces both the sensitivity and selectivity of the sensor array.

Synergistic Effect of TiS3 and Ti3C2Tx MXene for Temperature-Tunable p-/n-Type Gas Sensing

“…When TiS 3 is incorporated into the films, their resistance increases but the sensor response remains qualitatively the same; see Figure b. Interestingly, sensors based on pure TiS 3 also exhibit resistance increase upon their exposure to alcohols, so in Ti 3 C 2 T x -TiS 3 devices both components contribute to the observed sensor response at room temperature. The 75 wt % Ti 3 C 2 T x /25 wt % TiS 3 sensors showed a stable response to ethanol over the course of several days, as illustrated in Figure S1 in the Supporting Information.…”

“…Because of the weak interactions between these 1D chains, TiS 3 crystals typically exfoliate in the form of high-aspect-ratio nanoribbons with their long axes corresponding to the crystallographic b direction of TiS 3 . Overall, TiS 3 could be a promising material for gas sensor applications because of its semiconductor properties with a bandgap of ∼1 eV, very high theoretically predicted mobility, , highly anisotropic electronic and optoelectronic properties, − and intriguing low-temperature physics. − Several recent studies investigated solution exfoliation of TiS 3 and its applications in photodetectors, printed electronics, and gas sensing . In this study, we specifically focused on TiS 3 in combination with Ti 3 C 2 T x and found that the TiS 3 -Ti 3 C 2 T x sensors exhibit several improved characteristics compared to the sensors based on the pristine MXene material.…”

“…The p-type sensing response of the MXene gas sensors at room temperature is also improved by the addition of TiS 3 (Figure e). At room temperature, both Ti 3 C 2 T x and TiS 3 exhibit an increase in resistance on exposure to alcohols, ,, so these materials work collectively in composite Ti 3 C 2 T x -TiS 3 sensor devices.…”

“…40−44 Several recent studies investigated solution exfoliation of TiS 3 and its applications in photodetectors, 45 printed electronics, 46 and gas sensing. 47 In this study, we specifically focused on TiS 3 in combination with Ti 3 C 2 T x and found that the TiS 3 -Ti 3 C 2 T x sensors exhibit several improved characteristics compared to the sensors based on the pristine MXene material. Ti 3 C 2 T x MXene flakes were prepared using the minimally intensive layer delamination (MILD) method; 28 see the Experimental Section for details.…”

Electronic transport and polarization-dependent photoresponse in few-layered hafnium trisulfide (HfS3) nanoribbons

“…Because of their small thickness, the exfoliated TMTC flakes can be used for the measurements of gate-dependent electrical properties, which in recent years have gained significant interest in the case for TiS 3 [7][8][9][10][11][12][13][14][15][16] and, to a lesser extent, for ZrS 3 . [17][18][19] In particular, electrical measurements of TiS 3 revealed many interesting characteristics, such as an n-type transport, [7][8][9] a gate-dependent metal-insulator transition around 220 K, 13 gas sensing properties, 20 and a possible access to charge density wave physics at low temperatures. 2,10,15,21 Compared to TiS 3 and ZrS 3 , there were fewer studies on field-effect measurements on exfoliated HfS 3 flakes, 22,23 and some of the basic electronic properties of this material, such as its electrical conductivity and charge carrier mobilities, have not been reported as yet.…”